Lac de Derborence from Conthey

An absolute cracker of a route - the tunnels are amazing and not too scary - even though its one way. There are traffic lights to warn when the bus is coming. The tunnels themselves are fairly flat, so easy to do and there are quite a few open sides to let light in. Fantastic experience

Simply spectacular - after the steep climb to Aven the road turns at the corner into the valley and the gradient relaxesand then there are the tunnels. Wonderful road carved into the rock is wonderful to cycle through. The traffic was very light and only 1 bus had to pass us.
The Refuge is fine and it lets you see the lake, careful on the gravel and walkers/drivers

A nice climb: there is a quite steep section just after Aven, then it becomes much more manageable. After that, it is a bit shaded from the sun with a pleasantly cooling wind.
There may be some loose rock on the road, like going up the Sanetsch.
Lots of rock-carved tunnels: a light might be helpful, but there is almost no traffic as the road is a cul-de-sac.
The road becomes gravel if you want to see the Derborence lake or continue to the refuge. It should be beautiful in autumn!