The sea is located in the center of Blaine County. It is bordering Sandy Shores and Grand Senora Desert from the south, Mount Josiah and Raton Canyon from the west, Mount Chiliad from the northwest and Grapeseed from the northeast. It is very polluted. The player can participate in two triathlons there, namely Alamo Sea Triathlon and Coyote Cross County Triathlon, in which the player has to swim through the sea.
The water from the sea goes out into the Pacific Ocean through Lago Zancudo on the south and Raton Canyon on the north.
The area, due to its great size, has been involved in few myths.
Mount Chiliad Mystery
The Alamo Sea was frequently visited by myth hunters in order to find the Jetpack.
Many people claimed that some high-technology device might be located somewhere in its waters. One of the main evidence about these claims, is the mission Derailed, in which a Merryweather train filled with technology falls into the sea.
Another clue about an advanced device in the waters is the Merryweather Plane, which crashed into the sea after it was hijacked by Trevor Philips and was shot down by two P-996 Lazers.
On the sea's surface, it is possible to notice the face of Baphomet. At first it was thought that the face is a coincidence, but the cult activity in Blaine Country indicate it may be placed there on purpose.