It appears in GTA V. It is located at the north end of the Tongva Triangle, a hotspot of paranormal activity within the game. The wetland is located to the south of the heavily-guarded Fort Zancudo army base. As well as the river flowing down the middle, there are many pools and streams throughout the wetland area. Land areas are almost exclusively made up of deep mud that is difficult to cross on foot. Low grasses cover most of the wetland, with some scattered small trees and reeds close to the riverside. Overall, the terrain is very difficult to cross on foot and in most vehicles, except for SUVs and off-road vehicles. The player can wade through the most of the water.
The name Lago Zancudo is Spanish, and roughly translates to lake of the malarial mosquitoes. The Spanish name is reflected in Lago Zancudo's tourist motto, "bringing a taste of Mexico to the USA."
Lago Zancudo is said to be the home of the controversial myth of the Swamp Monster, which is rumored to reside in the westernmost area of the wetland, closest to the Pacific Ocean. It is also connected with several Fort Zancudo myths, due to its close proximity.
According to information boards along the Zancudo Wildlife Trail belonging to the Fellowship of Zancudo Wildlife Trust, the marshy areas of Lago Zancudo are inhabited by coyotes, brown bears, and beavers. Coyotes actually only appear around Sandy Shores and the Grand Senora Desert, and not around Lago Zancudo. More interestingly, however, is the mention of brown bears and beavers, which do not appear in the game, but are the subject of a myth, that says that they can be rarely found in Lago Zancudo.