Be aware of tides
Cancale is known as a fishing port, famous for its oysters. In fact, it's unoficially named as "France's Capital of Oysters".
But it also has lovely beaches. Be aware although that the tides here are among the greatest in France, with a swing of up to 14m between the high and low water marks. It was fun to go further and further in order to swim in the sea between high tide at about 10.00a.m. and low tide at about 4 p.m.
By 4 p.m. I was already swimming between the fishing boats.