Caumasee

The Caumasee sits in a hollow in the Flims landslide deposit, one of the largest rockslides known in the Alps, and it has no surface inflow at all - water arrives through the rubble from below, which is why it is so clear and why the level moves by several metres over the year, high after the melt and dropping through late summer. The colour is a strong turquoise where the shallow limestone floor reflects light. A small island sits near the middle. Swimming is the main activity, in water that is cold but not glacial, and rowing boats are hired from the lakeside restaurant. A small funicular saves the climb back up to Flims. The surrounding pine woods are part of the same landslide terrain.

What you actually see

• A lake fed from underneath - no inflow stream, water rising through rubble.
• A level that moves metres - high after melt, dropping by late summer.
• Turquoise over pale rock - the colour from the shallow limestone floor.
• A funicular back up - the alternative to the climb to Flims.

When to go

June to September. Half a day.

Honest expectations

It is extremely busy on hot weekends, and the small lido area fills. Late-summer drawdown widens the shore and can leave the boat jetty awkward. The walk down is easy, the walk back up less so. Entry to the bathing area is charged.

Nearby

Flims and Laax are above; the Rhine gorge is north.