Lac du Rotondu

Lac de Bettaniella is the largest natural freshwater lake in Corsica, sitting at 2,321 metres above sea level in the commune of Venaco, at the foot of the Monte Rotondo massif in Upper Corsica. It is also known as Lac de Bellebone or Lac du Rotondo. The lake measures roughly 425 by 225 metres and owes its existence to glacial activity: it is a classic glacial lake, cupped in a rocky basin with no significant surface outflow, making it an endorheic body of water.

Where is it and what does the landscape look like

The lake sits at the heart of the Monte Rotondo massif, whose summit rises about 300 metres above the water. The surrounding scenery is textbook high-altitude Corsica: bare granite slabs, glacial cirques and sparse alpine vegetation. Because the basin faces southeast and stays frozen for roughly seven months of the year, the setting keeps a raw, wintry character for most of the calendar — snow can linger well into late spring.

How do you get there

From the Petra Piana refuge

The most common starting point is the Petra Piana refuge (1,842 metres), a well-known stop on the GR20 long-distance trail. From there, reaching the lake takes a little over an hour to about ninety minutes. The first stretch is manageable, but the closer you get to the water, the steeper the path becomes, crossing boulder fields where hikers sometimes need to use their hands for balance.

Via Vizzavona and the GR20

An alternative approach starts from Vizzavona, a popular GR20 trailhead village. From there the route heads toward Petra Piana and continues on to the lake. It is a longer, full-day option, but it lets hikers combine the visit with a stretch of Corsica's legendary long-distance trail.

Climbing Monte Rotondo from the lake

For many hikers, Lac de Bettaniella is only a waypoint on the way to the summit of Monte Rotondo (2,622 metres) — the second-highest peak in Corsica, behind only Monte Cinto. From Petra Piana, reaching the top takes about three hours, with the lake passed after just under an hour of walking. The stretch above the lake is noticeably tougher: rocky terrain that occasionally calls for scrambling and extra care, especially when the surface is wet or icy. A full loop combining the Monte Rotondo ascent with a stop at the lake runs to roughly 9-10 hours for well-prepared hikers, with elevation gain in the region of 1,700 metres.

When to plan the hike

Given the altitude and the long snow season, safe hiking conditions are really only reliable in summer, from July through September. Outside that window the trail is often snow-covered or icy, and crossing the boulder fields becomes considerably riskier.

Frequently asked questions

Is Lac de Bettaniella the largest lake in Corsica? Yes, it is the island's largest natural freshwater lake, measuring about 425 by 225 metres.

What other names does the lake go by? It is also called Lac de Bellebone and Lac du Rotondo.

Where is the best place to start the hike? Most visitors set out from the Petra Piana refuge on the GR20, reaching the lake in 1 to 1.5 hours. A longer route via Vizzavona is also possible.

Can you climb Monte Rotondo from here? Yes, a steep, rocky trail continues from the lake to the 2,622-metre summit, Corsica's second-highest peak. The climb from Petra Piana to the top takes around three hours.

When is the best season to visit? Because the lake stays frozen for about seven months of the year, summer — from July to September — is the safest and most reliable time to hike here.