Kaji loves mingling at dog beaches. He never goes into the water. The only problem I've seen is humpers. Most pet parents are really good about watching their dogs, and most dogs there are so focused on playing with their owners that they don't bother anyone. I would wear shoes though. The dogs pee everywhere so it's best to keep your feet covered.
He's also gone to the beaches that allow dogs but they must be leashed. The only thing I don't like about those beaches is the restrictions. Most beaches near LA will only allow dogs on the beach from 5 am to 7 am, and then again in the afternoon from 5 pm to 7 pm. I might be a little off with the times since I looked these up months ago. The only beach where we can have fun on our schedule so far is the dog beach. Unless I drive down to Del Mar again. But they have crazier restrictions depending on the season. If I remember right, after memorial day dogs are restricted to a tiny portion of the beach.