Good place to walk - spectacular views of SF, people flying kites, two good on-the-water restaurants, a yacht harbor, a fishing pier, a playground if you go to the left at the fork as you drive up there, some wildlife (birds, ground squirrels) if you go to the right.
Some things to keep in mind - it's very windy, so take a jacket. It's very sunny, no shade anywhere, so take a hat/sunglasses. It's not in any way swimmable.
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