We recently went to Dog Beach in Del Mar and had a great time! There were several dogs there running around on the sand, retrieving balls in the water, and making new doggy friends. Since Penny is adopted, we are not sure if she has ever been to the beach or played in the ocean before. She looked a bit confused by the sand and the tide rushing up on her paws, but it didn't take long before she was running around enjoying herself.
This beach is along Coast Hwy 101, just West of the Del Mar Fairgrounds. You do need to pay to park so come prepared (the machine there takes bills and coin). I'm not sure if this beach is leash-free or not as most of the dogs were off leash, however, I think CA law is that your dog needs to be on a leash (so in other words, play it safe and bring the leash). What a fun time we had...we will definitely be back!