Country: USA
Address: RH4G+XW Fort Mason, San Francisco, CA, USA 
Classic swim in the generally very cold SF Bay. Often times there are sea lions in the area, but they generally mind their own business. Lots of folks out here on nice days (and a few crazy ones on the not-so-nice days!).
This is a swimming spot with salt water (seaside).
This is a swimming spot with a sandy beach!
Location on the map: