The Alamo Sea is a Natural Landmark in Grand Theft Auto V
It is located in the Blaine County, between Sandy Shores and Mount Chiliad
It is a big, salt-rich lake.
The areas around this lake are collectively referred to as "The Alamo Sea Region"
Background
Much like most of the local population, the Alamo Sea was born by accident and then left to fend for itself in a daily battle with chemicals. So salty even the fish have high blood pressure, the Alamo Sea is one of the few places on Earth where you can swim with three-quarters of your body out of the water, and some days even walk on water.