The Tataviam mountain range has a large body of water in its center and is located just outside of Los Santos, in the Northeast. To the north of Los Santos, located in the middle of Vinewood, is another large lake. Aside from the ocean, the largest body of water is the Alamo Sea, which feeds into several small rivers. The Alamo Sea is located to the west of Sandy Shores.
WASD movement keys on PC are as follows: W moves forwards, S moves back, A moves left, and D moves right.
You can attack while submerged or while treading water on the surface.