Just a quick reminder for people holidaying in France this year. Many public swimming pools and campsites insist that boys and men wear proper (lycra) swimming trunks in their pools. These can be traditional brief style, swim shorts or jammers but must be tight around the leg for hygiene purposes. Looser swim shorts are not allowed.
I'm currently on holiday in France and have seen a number of men asked to leave the pool because they were not wearing appropriate swimwear.