When I adopted my first golden (he was 1.5 years old) in April 2000, I used to bring him down to Monterey from Morgan Hill (where I lived at the time). Charlie was interested in the water, but got knocked over by a wave and then refused to go in. We continued to play in the sand, then went home. We went back the following weekend, and another person and their dog were playing, Charlie started playing with the dog, and the other dog got him into the water and swimming
He was a swimmer ever after! The beach in Monterey *was* dog friendly, which is why we went there.
There's a reservoir in Morgan Hill off Dunne Ave I used to bring him up to, until on one of our walks he jumped over a rattle snake; after that I only brought him to the parking area that had direct access to the water, no more hiking there for us. (I'm a well documented wuss).
I used to bring him to the dog-friendly beach in Santa Cruz, until he got caught swimming after a tennis ball near some very aggressive waves, almost feeling like it could be a rip tide - he barely escaped that; I was about to go in after him when he managed to get out of whatever that crazy churning was and get back to shore. I never felt good bringing him there again. It was the area over to the far left of the beach; I'm sure it's a safe area because it is dog-friendly, but that incident scared me so I avoided going there again.
Again, this was all a fairly long time ago when I lived in the Bay Area; I'm closer to Lake Folsom and Tahoe now and will be bringing our 5.5 month old pup up there after he gets his rattlesnake and lyme boosters next week (probably in May, just to be sure with the vax).
ps: Summer is gorgeous!!! Have fun finding new places to swim