Lac du Der. Again

We last came to France three years ago and stayed at this lake. I was not very impressed. A few evenings ago LooseCanon said he had booked a nice campsite by a big lake. The campsite we are at is indeed lovely with a pool and a little cafe and bar. But as we were approaching I recognised the name of the lake and it’s the same lake I so despised before!
It’s been incredibly hot today and we decided to cycle round the said lake having remembered that bits of it were much better than where we had been staying before. 
It’s a strange place I think, a manmade lake to appeal to those who live about as far from the sea as you can get in France. It has lots of water birds and we saw what I think were dozens of Purple Emperor butterflies.  But at a couple of areas where people were bathing it really didn’t look very inviting with green algae and imported sand. 
I’m really NOT coming here again. But we did have an enjoyable thirty mile bike ride ( with a bit of battery pedal assistance) .  And the campsite is excellent.