(1) From the car park just before the information boards, take the path that descends towards the stream.
Cross it via the footbridge, then follow the path (marked in yellow) which climbs gently through the forest for 800 metres and then becomes much steeper. A sign indicates "Lac des Adus 1h45".
(2) At marker 396, head straight towards the refuge, pass it and stay on the left-hand path at marker 395. The lake is not far away.
(3) For the return journey, ignore a path on the left, cross to the other side of the lake, head towards the refuge keeping to the right, then descend via the same route as on the way up.
