The GR5 versus “Les Balcons du Mercantour”
Routes from Larche through the Tinée Region to the Vesubie.
Do take a rest day in Larche.
Be sure to carry extra water (at least 2 liters)on all the routes from Larche south as there are no sources of drinkable water, in many cases no water at all, between the towns or refuges.
Information and a reservation page for all the Mercantour refuges can be found following the links at http://www.cafnice.org
Routes between Larche and the Vesubie River
Several paragraphs below, I highly recommend a choice of several routes for intrepid walkers that deviate from the GR5 – 52 for five or six days. It takes one or two fewer days to the GR52 to Menton and visits some exciting terrain in comparison to the official GR5 route and the first long day of the GR52, all of which I find rather dull. Also, you spend two nights in Italy, with a chance to experience that culture.
The route (or choice of routes) I recommend follows what the Alpes-Maritimes hiking officials are now calling “The Balconies of the Mercantour“.
If you are taking the GR52, the total walking time to Boréon via the official GR5-52 route is 7 days (39 hours). On my more beautiful and exciting routes it is 5 or 6 days (28 1/2 or 31 1/2 hours). You save 8 to 10 hours of walking and have a much more interesting trip. (Check out the photos below to see if you wish to detour from the official GR5.)
Also below you will find a tip for easygoers, short of time, to quickly reach the GR52 rather than remaining on the less interesting GR5.
Day numbers below are from Larche.
GPS Coordinates — only available on this page of the site — are taken from readings on Google Earth are are approximate.
Day 1, Part 1, All Routes: from Larche to the Pas de Cavale.
Important: Ask at the Gîte de Larche about snow conditions on the Pas de Cavale (2671 meters, 8763 feet). If they tell you it is blocked with snow, as it may be into late-July (as was the case on my second visit), the same “Salse Moraine Valley” shown in the photo below and the GR5 there may be joined by a somewhat lower trail via the Col de Pouriac (2506 m, 8221 ft). The trailhead is in Italy, four kilometers southeast of the GR5 on the main highway from Larche. Figure that this detour will add an hour and one-half to your walking time, more if you have to contend with snow banks. If you are an easy going walker, offer to pay the gite owner or a hotel employee to transport you to the Italian trailhead by car. In that case your total time walking time will be at lest 3 hours less.
If you are going to follow my special route described below, I highly recommend that you set out from Larche (1,675 meters, 5,500 feet) by flashlight before dawn. You will want to be off the high and exposed passes before mid-afternoon. So if you are staying in the Gîte de Larche or a Larche hotel, ask if they will lay out coffee and bread for you the night before. In general, from Larche to the Mediterranean, it is wise to set off at 6 or 7 in the morning, to do your climbing before the sun is overhead.
Whatever your final destination, you leave Larche by the highway and quickly branch onto a minor road, which, after an hour, curves southwards and enters the Mercantour National Park. Now on a trail, the GR5 climbs to the Pas de la Cavale at 2,671 meters (8,763 feet) in a total of 4 1/2 hours (not including rest stops). Looking ahead from the pass of the Pas de la Cavale, the scenery resembles a moonscape.
From the Pas de Cavale
Notice the Lac d’Angel on left below. The trail to Bouziéyas runs from there along dried river towards the right.
The following photo is to the left of the one above, with a wider angle view.
If you are taking the Lac de Vens route described below —which requires route-finding — now, at the pass, is the time to study your map and my photo carefully, and to match landmarks.
Descend on the GR5 to the lakes d’Angel in the Salse Moraine Valley at 2,343 meters Looking back now at the Pas de Cavalle pass, you will wonder how you ever came down the cliff.
Looking back at the Pas de Cavale from Lac d’Angel.
Day 1, Part 2 and days to the Vesubie
Option 1 – GR5 Route:
Day 1, Part 2 and days 2,3,4,5 and 6 (+1 for the GR52 to Boreon
The GR5 bears slightly to the right, and continues to the Refuge of Bouziéyas (at 1,883 meters) in just over two hours.
Town of Bouziéyas. In the distance on the left, where GR5 crosses the pass tomorrow to St-Etienne-de-Tinée
Lodgings are infrequent in the Alps Maritimes, so you have only a few choices: After the 7 hour, highly vertical day from Larche to Bousiéyas, it would be desirable to have a light day and to stay in an urban setting for a change, so you might wish to select a 5 1/2 hour walk to the pleasant and picturesque old town of St.-Etienne-de-Tinée (day 2).
Tip for Easygoers, short of time, wishing to hike the GR52 route to the Vallée of Merveilles and Menton:
Take a bus from Saint-Etiènne-de-Tinée to Isola Isola Village and transfer to the bus to Isola 2000, arriving at midday – no more than 4 Euros), or a taxi from Saint-Etiènne-de-Tinée (33 kilometers) or from Bouziéyas the day before, about 46 kilometers plus 13 kilometers for the cab to come from St-Etienne-de-Tinée).
From Isola 2000, the same day, walk to Boréan in 5 to 5 1/2 hours. See below for walking directions. This gains 5 days from Saint-Etiènne-de-Tinée or 6 days from Bouziéyas compared to the official GR5–GR52 route, missing GR5 terrain that is not so interesting.
Continuing from St-Etienne-de-Tinée
If you stay in St. Etienne, then it is a short day of about 4 1/2 hours via Auron to the Gîte d’étape at Roya (day 3) , followed by a 6 1/2 hour day to the fine Gîte d’etape at Longon (day 4). This is easily manageable, but note that after Roya you will be walking on completely bare mountain ridges with no water, and without shade. Then you have a 4 hour walk to Saint Saveur-sur-Tinnée (day 5) and another 4 hour walk to Saint Dalmas-Valdeblore (day 6).
You could lessen the number of days to 5 if you stay in Auron, and walk a very long 10 hour day to Roya.
The GR 52 branches off in Saint Dalmas-Valdeblore to the north, with a 4 hour climb, mostly on bare ridges, to the Col du Barn, and an almost equal descent of 3 hours to Boréon (day 7 from Larche).
Tips for easygoers on June weekends and in July and August: Take the Telecabine de la Pinatelle up from St-Etienne-de-Tinée, and follow the dirt road, with a slight loss of altitude, into Auron. Take the chair lift de Blainon to the top station and walk down the ridge to the pass.
View of Auron and GR5
On leaving Auron, after crossing the lift clearing, mountain bike trails confuse the way and there is no sign for the GR5. Keep left here,where the poles are, straigh ton:
View from Col du Blainon towards Roya and Mount Mounier:
Boucatin grazing, on side of Mt. Mounier, side-trip above the Col de Crousett.
Looking back north towards Roya, note that the GR 5 runs for long distances over treeless ridges.
View towards, on right, the Pas de Barn climbing from Saint-Dalmas-Valdeblore on the GR52.
Note that there is no shade.
Day 1, Part 2 and days 2,3,4,5 and 6 to the Vesubie – The shorter, more interesting (and more challenging) alternative to the to the GR52: The “Balconies of the Mercantour”
The Balconies of the Mercantour route was originally concieved of to follow the alpine crest entirely in France, but was never completed but in fact requires excursions into Italy. A link opened in late 2008 that makes the entire route accessible to average hikers if snow is off the trail. The first half of the route takes place in wild, pristine high-mountain country unique in an Alpine Crossing to the Mediterranean. The second half visits beautiful vistas, but is more civilized.
An examination of the French on-line Geoportail.gov hiking map in 2020 suggests that the Balconies of the Mercantour route in France may have been extended. If so it covers some very steep terrain. I have never walked the last part and cannot comment on its safety, or timing. Inquire at the Refuge de Rabuons.
I give the Balconies of the Mercantour route, which I strongly prefer to the GR5, extensive treatment below, because I don’t believe you will find this route described in detail anywhere else in English.The Balconies Route not only is starkly beautiful and scenically different from the rest of the Alpine Crossing, but it is a shorter by a day or even two to the Mediterranean. You should be able to judge from the pictures on this page whether the Balconies route is for you.
The GR 5 guide book maps do not cover this area. You should purchase the IGN maps 3639 OT “Haute Tinée 1” and 3640 ET “Haute Tinée 2” (€12 each in 2016) or print out your own maps from screenshots of tab.geoportail.fr
Day 1, Part 2 (to the Refuge de Vens rather than via Bouziéyas — a high mountain, path-finding route, but not requiring special skills)
Days 1 and 2 on the GR5 or the Mercantour Balcons route, from the Pas de Cavalle
Salse Moraine Valley from the Pas de Cavale. The off-trail route passes
on this side of the high, black and green ridges running from the right to the center of photo; then, turning right, it passes out of view, before the mountains in distance.
See the large photo above that has a dot to mark your intermediate destination.
The first day of the route requires climbing, in addition to the 1000 meters to the Pas de Cavalle, after a descent, another climb of 500 meters. Also, for those not used to walking off trail, this route may be scary. Both times I walked the route, my companions felt completely lost because we could not see from below where we were going and suggested turning back. These days, those using GPS may have a better sense of security. The very qualities that makes this route scary to some makes it one of my favorite routes. However, do not undertake the route alone, because, in the unlikely event of an accident, you are not likely to meet anyone else on the way (and that is especially true in June or September).
Needless to say, don’t attempt this route if there is the least sign of thunderstorms, or if thre is fog on the peaks; the “Col de Fer” on this route means “pass of iron”, and this pass is known to attract lightning hits. Also don’t attemmpt this route if your physical stamina is low.
Directions from the Pas de Cavalle to the Refuge du Vens: . Allow 4 walking hours from the Pas de Cavalle to the Refuge de Vens. This comes to about an 8 1/2 hours of walking from Larche. Decend from the Pas de Cavalle to the lakes —Lacs d’Angel on the GR5 (appx. GPS 44º21’09.73”N, 6º53’04.89″E). Stay left of the lakes, and descend to about 2200 meters (Appx. GPS: 44º20’51.13”N6º53’41.03E), crossing the dry river. At the bottom of the rounded ridge, bear left. Begin climbing .Once you have passed by the top edge of the rounded ridge that will have blocked your view to the right, a series of little lakes becomes visible, and you will keep these on your right as you continue to climb, passing the uppermost little lake, and enetering a sort of a mini-valley that has a trail in it, running off slightly to the right. to the Pas de Morgon (appx GPS 44º20’00.15”N 6º55’34.11″ ). You are almost at the same elevation as the Pas de Cavalle.
Looking back during the climb. Little lakes are below
towards left. Pas de Cavale, from which you came,
is located just left of middle of photo. The Italian pass is to the right.
Now the trail is on a ridge, somewhat exposed on both sides, following cairns. At the end of the ridge, you turn sharply right by about 135 degrees, angling backwards down the slope, and at the bottom turn sharply left again on a faint trail that soon meets another, better and waymarked trail that comes up from the right (and soon another from the left at the Col du Fer, 2,684 meters, 8,674 feet (44º1936.14”N, 6º56’84.58’E’).
Refuge and lake of Vens.
Continue to the Collet Tortisse , 2591m (44º19’22,72”N,6º56’12.66”E), and descend to the Refuge de Vens, at 2,366 meters, 7762 feet, on a lake of the same name. This is one of the wildest corners of France. In resume, on this day from Larche you climb 1000 meters, descend 500, climb 500 and descend 300.
If the weather was not conducive to the route finding, it is possible to reach the Refuge de Vens from the gîte d’étape at Bousiéyas, by walking on the road 2 or 3 kilometers to le Pra, and then taking the marked trail which leads up to the Refuge de Vens, either directly in 4 hours or via the Col du Fer in 5 hours. If you come to Vens via this route through Bousieyas, it adds a day to your trip. But you could skip Vens and walk directly to the Rabuons refuge, in which case you do not lose a day (total walking time from Bousieyas to the Rabuons refuge is about 8 hours).
I remember my visits to this stark and remote country as being very much worth the effort and the detour. My companions—who liked more civilized surroundings, staying on a wide trail, and less effort—did not agree.
Day 2: Continuing from the Refuge de Vens to the Refuge de Rabuons on the Balcons du Mercantour route.
Note: You can leave the special route, descending from the Refuge de Vens to Saint-Etienne-du-Tinée to rejoin the GR5 without losing a day or having climbed extra elevation.To do so, following trail signs, climb 300 meters (1,000 feet) and descend 1300 meters (4,000 feet) in about 4 1/2 hours.
From the Refuge du Vens (signpost #25), the trail passes along the north side of the Vens lakes. Make a brief detour to see the view where a stream exits to the lip of the plateau. Then, after passing another lake, climb over a pass. After the pass bear left and climb slightly onto the Chemin de l’Energie—a true road (but with no way to drive to it) built between the World Wars to permit construction of a hydroelectric plant (that never materialized). About 5 kilometers long and practically level, the Chemin continuously has excellent views of the Tinée valley until, near the end, it passes through two tunnels. (An extra hour is necessary to detour via the Plan de Tinebre, as shown on the map, if the repairs to the tunnels have not been completed.) Climb briefly to the Refuge de Rabuons (tel.04 93 23 04 11) at 2,510 meters, located beside a lake and sourrounded on three sides by foreboding mountains of black rocks. The Rabuons refuge is isolated, basic and small, but has a wonderful ambiance, a solar shower, and cheerful service. (See the refuge on its “rock” by enlarging the second photo below.) Walking time from the Refuge de Vens is 4 hours.
There is a high route over Mount Tinebre to Rabuons for mountaineers —quite exposed and difficult, that usually requires crampons and ice ax. Check with the staff at the Refuge de Vens if you are a mountaineer.
Tunnels on the “Energy Road”, seen from the trail to the valley.
From the Rabuons refuge (2,523 meters), if you should wish to rejoing the GR5, you can descend to St.-Étienne-de-Tinnée (1,300 meters – 4,000 feet) in under 4 hours.
Days 3 and 4: Continuation of the Balcons du Mercantour Route to Refuge Laus and Sant’ Anna, in Italy, or possibly continue further to Isola 2000
You can walk this section from the Rabuon refuge: (A) on walking trails or (B) on mountaineering trails.
On day 3, Mountaineering (A): If (big if) the snow is off the Corborant pass (3007 m – 9,900 ft), AND you are willing to use your hands a bit, AND if you are willing to descend a scree slope… AND if you are willing to climb 500 meters (1,500 feet), descend 1,400 meters ( 4,600 feet), and climb again 300 meters (1,000 feet) you can take the Corborant pass to the Alexandris Foches (Laus) Refuge in about 5 or so hours not counting stops. Otherwise there is a lower level route with no scrambling that takes 6 hours.
On Day 4(A): There is the exciting crest route that involves walking on a slanted hillside where a slip would be very bad and the crossing of a narrow, exposed pass with a 300 meter drop.
Otherwise, On day 3 (B): You can take the recently opened (fall 2008) route, lower in altitude (highest point about 2650 m), but longer in distance and time, trail to the Laus refuge. It involves an assent of approximately 130 meters (400 feet), a descent of 500 meters (1,600 feet), another assent of 400 meters (1,300 feet), and another descent of 650 meters (2,100 feet). This would take 6 or so walking hours.
On day 4: You can walk the easy low route to the Sant’ Anna Sanctuary in 4 hours and perhaps even continue to Isola 2000.
Details on Day 3 Option A
Refuge (on left) and Lac du Rabuons looking back from new trail .
In the summer of 2009 I used the newly created trail now visible on tab.geoportail.gouv.fr (click the list of “donées” to add the IGN maps) and on the recent IGN paper map of the area. It runs southeast along the French side of the crest. I can recommend this trail for average walkers provided all the snow is off the trail. Ask at the Rabuons refuge if the trail is clear (in a normal year by mid-July), making very clear to them your level of skill. (The guardian, being a mountaineer, as in most refuges, is likely to assume that it is easy to go around snowfields by climbing up and down the rocks, or to hack out steps to cross them.) If there is snow on the trail, descend to St. Etienne-de-Tinée, and either follow the GR 5 or if you are not a “purist”, take a bus or a taxi to Isola 2000 and pick up the Boreon trail there, saving a day or two.
The bowl on the new trail
View from the new trail towards Auron village across the valley, where the GR5 passes, 1000 meters (3,300 feet) below this level . The GR5 is visible center-left.
The new trail is wide, about one-half the width of a road lane. From Rabuons it climbs to the south, crosses a col, and contours around a bowl (see two photos immediately below), all over slabs of rock and stones.
The rock-filled bowl below. Trail climbs on right.
This portion is slow going, taking about 2 hours, as you much watch your step .
Leaving the bowl, the trail is in normal grass and you can double or triple your speed. Another hour bring you to a signposted cross trail . If bad weather has suddenly rolled in, you can descend to Douans in the valley (1100 meters below). Otherwise, turn left and climb to the Pas de Colle Longue at the Italian border.
The gardian of the Rabuons refuge warned me not to take any of the other trails to Italy indicated by dashed lines on some maps (but not easily visible from the new route), because they have not been maintained and are quite dangerous.
Climb to the Pas de Colle Longue
The climb from the above-mentioned trail junction takes a good hour, mostly through beautiful rolling meadows full of sheep. There is only one short somewhat exposed portion of the trail where you must watch your step. At the col one sees the remains of military fortifications and barbed wire. You spot the Lake (not the village) of St. Bernalfo, near the refuge, 650 meters below, about an hour and one-half by the sinuous closed-off road and/or the partial trail. I saw three chamoix in this valley. The refuge is five minutes to the left of the lake, just over the crest of a hill on the road (Tel Italy (39) 0171-959-606). The refuge is open continuously during July and August and on weekends from May to October. When the refuge is closed, it may be possible to use a matress in the winter bivouac room, if you are carrying your own food. Call for details.Figure about 6 hours in all from Rabuons. Via this routing, you will definitely want to spend the night at the Refuge Alexandris Foches at Laus.
Refuge Alexandris Foches at Laus
Since it was mid-week in July, I had a room with four bunk beds for myself, and never met anyone in the bathrooom. The meal consisted of four courses: pasta; meat; cheese; fruit.
Day 4: From Refuge Laus to Sant Anna:
It is possible to combine this day with the next one to make one long day of 7 or 8 hours from Laus to Isola 2000.
Santuario Sant’ Anna di Vinadio (tel. Italy (39)0171-959-125 https://www.santuariosantanna.eu/en/), your destination, is a sanctuary for travelers, a place of worship, and a famous pilgrimage destination in Italy. The sanctuary was founded hundreds of years ago to serve travelers and thus also runs what amounts to a hotel and also refuge. It was nice for a change to have sheets, large towels and my own bathroom, and to enjoy watching the mixture of pilgrims and tourists. The menu at Santa Anna was similar to the night before, three courses – typically pasta followed by meat and vegetables, followed by dessert. Santa Anna has a separate snack bar open at lunch with sandwiches, pies and drinks. The beautiful church there is poised on a rock slap, and its floor slants up to the altar.
Details on the two ways of going from Laus to Sant’ Anna:
A) The exciting, risky, crest route near the French-Italian border: In 2009 I took the crest route from Laus, which involved climbing up to the Paso del Bue (Pas du Boeuf) (Beef Pass) (a climb of 700 meters from Laus). Average walkers: avoid this route; you must be sure-footed, very careful, and willing to undergo exposure to heights.
The trail to the pass was badly maintained in several places, and required walking several hundred meters (yards) in footsteps on a steeply sideways-slanted hillside. In other words, it was a bit dangerous and absolutely required fabulous balance or trekking poles! The Paso del Bue is narrow and quite exposed (see photobelow).
Looking back (down) from the Passo del Bue (Pas de Boeuf) (a military building on a snow patch is visable as well as the trail over the snow)
Passo del Bue
After the pass, the trail continues over slabs of rock and stones for about 1 mile before reaching dirt. In the photo above, the trail runs about one-third of the way down the slope just beneath the cliffs, and turns right into a gap in the ridge. Some maps show a trail along the very crest between France and Italy, but the Laus guardian told me that this was very dangerous. The correct trail shown in the photo is now on the Geoportail site and on recent IGN maps.
At a branch in the trail in view of a stone military building, a direct trail to the left leads towards the pass, but it looked eroded and dangerous; I chose to go to the right, scrambling up an eroded slope to a better trail that went in front of the military structure. From there, after a flat stretch, it takes some scrambling up steep somewhat slippery slope on an eroded but safe-enough trail to the Paso Saboulé. From the pass, you can choose between two very good trails is to Santa Anna. The shorter route, by perhaps one-half hour goes left to the Passo Tesina. The longer route crosses into France, passes by some nice alpine lakes before crossing back into Italy on a road carved steeply into the mountainside (here I saw two bouquetin), and descends by a closed-off unpaved military road from WWII to Santa Anna. Total walking time is about 6 hours. The mountaining route described above, while exciting, should only be taken by those equipped with trekking poles, and who are wiling to undergo a degree of risk, exposure, and difficulty, and not by the average trail walker.
B) The route for regular walkers from the Laus refuge to Santa Anna
The last few minutes to Santa Anna are on a tarred road.
This route involves going down to Callieri, (a descent of about 450 meters). From Callieri the trail leads directly to Santa Anna via the Tesina Pass (a climb of 1,000 meters and a 400 meter descent). This 4 hour routing though unexciting, is pretty, easy and safe.
If you are are combining this day with the next one, you will save almost an hour by not descending all the way to Sant’ Anna.
Day 5: From Santa Anna to Isola 2000 (or Boréon
An steep but safe trail leads from Santa Anna up to the ridge line in one hour, and then in another hour to the Col de Lombarde, above Isola 2000. If the weather is inclement, or if you wish shade, you can walk up the military road in the valley in even less total time. I descend from Santa Anna on a trail to a track that eventually joins the main road, and then bypass the road switchbacks to reach the pass. The descent to the ski village can be accomplished in less than an hour by the ski slopes or perhaps in an hour by a marked trail that winds over scree before descending. Total time is under 3 hours.
Isola 2000. Straight ahead is the Col Mercière, your continuation
As the name indicates, Isola 2000 is at an altitude of 2000 meters. This ski village, like Auron on the GR5, has a number of unattractive buildings that may offend many hikers who prefer infrenquented pristine areas, but it can be bypassed only by saying in Italian refuges and climbing high passes that add a day of walking to the GR52. There are only two hotels in Isola 2000: the Hotel Druos ** in summer almost always has last-minute nice rooms without board at a reasonable price; the Pas de Loup***, less available, includes all meals. There is no gite d’étape or refuge. The restaurants, such as the popular La Marmotte or La Raclette, specialize in alpine cuisine, but also serve traditional French cafe dishes. The hotels in Isola 2000 are connected together side by side, and under them can be found a continuing passageway – shopping mall. Walk through the mall and you will come upon the market, shops and restaurants Most stores will be closed on Sunday and from 12:30 to 3:00. There is bus service to Nice.
Many walkers who have stayed in Sant’ Anna may prefer to continue directly to Boréon in one fairly easy day of 7 hours. By taking the trail to the left from the road after the ski lift crossing and branching off left at trail marker 91 you can save 100 meters of descent, bypassing Isola 2000.
Day 6: From Isola 2000 to Le Boreon on the GR52 or St. Dalmas-Valdeblore on the GR5
For those who wish to spend a week on the GR52, a Lignes d’Azur bus on line 750 leaves at 9:00 AM (2018) from the bus station in Nice and arrives at Isola 2000 at 11:30 AM. A pleasant walk will put you in Boréon by late afternoon. It is also possible to reach Boréon directly by bus on Lignes d’Azur #730 from Nice, departing at 8:15 or 9:15, to St. Martin-Vesubie,arriving at 10 or 11 AM, and then transfering to a shuttle (navette) to Boræeon, or take a taxi to Borón or to Madonna de Fenestre.
It takes just over an hour from the Isola 2000 village to climb to the Col de Mercière at 2,343 meters. From there in summer you can descend through the fields, cutting off the curves of the sinuous dirt road that forms the official trail, until you reach the lovely pine, larch and fir forest.
You walk easily through this enjoyable forest on a dirt road closed to traffic, first descending, then almost keeping level, for 1 1/2 or 2 hours until the Col de Salesé (2031). Just before the col you meet and join the GR52. You are now off the Haute Tinée 2 map and on the Vesubie map, but on the GR52 map if you are using a French Topoguide. In any case, the route is signposted and waymarked. From the col you descend on a highly trampled trail to the Parking area in 1 hour, and then by the tarred road to Boreon (1526 m) in another 1/2 hour. Total time is 5 to 5 1/2 hours.
A wolf sanctuary in Le Boreon—containing about 20 wolves—may be toured in a couple of hours. Le Boreon has a pleasant lake, much visited by tourists for the day, and a restaurant serving trout you are supposed to catch yourself (but they bend the rules). There is at least one hotel and also in a Gite d’étape, as well as bus service to Nice. As you are now on the GR52, covered in detail in a topoguide, so my detailed trail description ends with Boreon.
Should you wish to rejoin the GR5 rather than walk the GR52 (see my discussion of the choice between the two on the next page), just before the Col de Salesé (after about 3.5 hours of easy walking from Isola 2000) you must take the GR52 in the opposite direction . The topoguide walking time from this point to St. Dalmas-Valdeblore is about 4h50m, or about 8.5 hours from Isola 2000. There is no intermediate lodging point, unless you bivouac near small lakes 20 minutes below the Pas de Barn. (If you are willing to walk to St. Dalmas-Valdeblore by an alternative to the GR52, it appears from maps that you could save at least an hour and perhaps two by going via the abandoned hamlet of Mollières.)
The Balcons du Mercantour trails described above are worthy of your strong consideration. They provide the stark beauty of a truly high level route; the excitment of some more difficult trails—if you choose them; the novelty of an excursion into Italy; and a savings of one or two days walking time if you are continuing on the GR52.