Hive Pocket is beachproof, small, easy to learn but hard to master, and a lot of fun :)

There’s a beach set of Uno with laminated cards. Classic.

I particularly enjoy Cabo & Phase 10 for their replayability.

Oink games always have really compact games, super small boxes. Very easy to put one into a bag or something. Some of them to have a lot of tokens so I’m not sure if it’s a great idea to play on the beach. A good place to start:

• Scout

• Insider

• Deep Sea Adventure

• Startups

• A Fake Artist Goes to New York

• Love Letter

• You‘re bluffing (competitive auction/bluffing/set collection)
• Bohnanza (competitive trading)
• The Crew (cooperative trick taking)
• Hanabi (cooperative set collection)

I would also recommend Azul. I think its super easy but can have some depth to it. It has heavy pieces that should not fly away so easily. The sand of the beach will not be much of a problem either, besides that its sand. Tracking the points might be better done with a pebble or something.