Based on the UH-3 Sea King, the Leviathan is the second largest helicopter on the game and has the ability to land on water thanks to its boat-shaped hull. It is very slow and sluggish, slowly ascends, and strangely has the same rotor sound as the Hunter, Cargobob and Raindance. Its name comes from the mythological creature of the same name.
The Leviathan is used in the mission Up, Up and Away! in which the helicopter has a crane with a magnet attached to the bottom that can be used to lift vehicles. There is no way to obtain any helicopter with a magnet like this outside of this mission, but some mods may enable the Leviathan to have a magnet crane attached to it. The Leviathan from this mission can be saved, but its magnet will not be saved in the garage. Once completing the mission, a Leviathan will spawn at Verdant Meadows, but it does not come with a magnet.
It is also seen in the mission Interdiction to drop a package, and Carl has to protect it from the two FBI choppers that give chase.
Verdant Meadows after completing Up, Up and Away! Note that when both the Leviathan and Hunter are unlocked, only one of them can spawn at a time. Arrive from the west to spawn the Hunter and arrive from the east to spawn the Leviathan.
Leviathan is a fearsome monster described in the Bible, believed by scholars to be a rather embellished description of a crocodile but usually depicted as a sea serpent. As a general word, it is used to describe anything extremely large.
It is one of the 4 vehicles in the game named after a mythical creature, the other 3 being the Banshee, Hydra and the Phoenix.
Like most other aircraft in GTA San Andreas, the Leviathan plays K-DST by default.