One of the biggest disadvantages here in Switzerland - it does not have direct access to the sea. But as a nice compensation it has a lot of beautiful lakes. Some of them are so huge, that they are very similar to the sea.
My favorite one - the lake of Neuchatel. It is still not so populated as many other splendid swiss lakes. The water here mostly very clean and warm in summer. Coasts are very different - You can find here every beach you like: sand beach, gravel beach or even grass beach in the coastal forest.
Paddling, swimming or just walking near the shore would be always very nice