From Saint-Dalmas de Tende (06), take the D91 road towards Castérino. In the village, carry on to the upper car park.
(S/E) From the car park, head for marker 395 and enter the Mercantour National Park. Begin a gentle climb along the yellow-marked path to reach the first junction near a wayside shrine.
(1) Continue to the right on thePR®® trail, passing marker 392 which points to the right towards Lac des Grenouilles.
(2) Carry on straight ahead along the track to a junction near marker 390.
(3) Just before marker 390, take the path towards the Refuge de Fontanalba. Continue along the track to the refuge.
(4) Immediately after the refuge, turn right onto the path that cuts across a bend in the track. Return to the track until you reach marker 387.
(5) Cross the small bridge on the right and you’ll reach marker 388 very quickly. From this point, you enter the restricted area containing the rock carvings of Les Merveilles and Fontanalba.
From marker 388, continue towards the Lacs Jumeaux, leaving the Lac Vert path on your left. Pass in front of the Gias des Pasteurs (a small sheepfold) and reach the start of the Voie Sacrée.
(6) Climb the steps of the ‘Voie Sacrée’. As you go, admire the rock carvings. Pass the path leading down to the Lacs Jumeaux and follow the start of a track that climbs north-west.
On the grassy slope, reach a small flat area, then take a narrow gully on the right (the bed of the stream flowing down to the Lacs Jumeaux).
Climb up the gully through scree, grass and rocks, which leads to the ridge (with occasional traces of a path). Continue until you reach the foot of the ridge.
Caution: Do not climb right up to the very edge of the ridge.
(7) Veer left just before the ridge. Follow a path below the ridge at times, through the rocks, until you reach a point where the summit is finally clearly visible.
(8) Climb the grassy slope towards the summit of Mont Sainte-Marie.
(9) Follow the ridge along the rocks of Sainte-Marie to a large fault.
(10) Descend below the ridge to join a good path a little further down. Pass at the foot of the Cime de Bicknell. Continue to marker 397, which is the Baisse de Fontanalbe marker.
(11) Head down the path on the right. This is the Baisse de Valmasque path leading to the Valmasque Refuge as far as marker 96.
(12) Carry on to the right towards the Valmasque Refuge, skirting the Lacs du Basto and Lac Noir.
(13) Then pass Lac Vert to reach marker 97.
(14) Turn right (leaving the path leading to the refuge on your left). Descend to reach marker 98.
Descend the entire valley to marker 374, the standard route to Castérino.
(15) Continue along the track to reach marker 393. Follow the right bank of the Ruisseau de Valmasque. Leave the stream when it joins the track and keep parallel to it to reach marker 394 at the gate marking the park entrance. A few more metres to reach the car park (S/E).