The Los Santos Naval Port is a large facility located on Elysian Island in the Port of Los Santos in Grand Theft Auto V. It is a restricted military installation guarded by Merryweather Security. In Grand Theft Auto Online, the facility is completely unrestricted; even the helicopters parked at the end are free to take.
The Port is composed primarily of a massive warehouse and dock complex. Its central bay consists of two large slips for naval vessels. The warehouse also holds a partially deconstructed Soviet/Russian Alfa-class attack submarine. Otherwise, the warehouse consists of staircases, catwalks, and offices.
There are three entrances along the Port's northern face. The central main entrance provides a view to the inside of the warehouse. There is a guard house manned by a Merryweather Security guard as well as a gate that does not open when the player approaches. The other two entrances, to the east and west of the main gate, grant access to large rooms. Both rooms contain plywood building mock-ups that appear designed to accomodate Merryweather attack drills.
The main warehouse is accessible either by circling around the eastern edge of the structure or by swimming along the western edge and then taking a ladder up to the pier. Entering the warehouse or ascending to the pier leads to a four-star wanted level. Even without entering the warehouse or pier, Merryweather Security guards may still attack if the player spends too much time in the area. Later in the game (at least post-The Bureau Raid, possibly earlier), Merryweather guards will no longer be found in the facility. Entering will still trigger a four-star wanted level, but the player will be free to roam around (or make their escape) until law enforcement arrives.