" Les Buttes de Trélazé " it's also what we call its ' trous d'eau " ,looking like artificial lakes It's forbidden...

" Les Buttes de Trélazé " it's also what we call its ' trous d'eau " ,looking like artificial lakes It's forbidden to swim because of the steep depth .
They are used for firemen , diving clubs who come there to train .
In Summer , the water is hot because of the slates .