The word lagoon in English, and laguna in Spanish, generally describes a body of shallow brackish water, usually next to the sea.

Laguna Catemaco was formed millennia ago, when lava flow from San Martin Tuxtla volcano blocked its current northern end, and stands now at 340 m (1,115 ft) above sea level.

The laguna drains via the Rio Grande de Catemaco and its water level is controlled by several dams which replaced historic waterfalls.

Eyipantla Falls (Salto de Eyipanlta) is a 45-meter high waterfall on the Rio Grande, located 11 kilometers downstream from the lake.

[1] The lake is polymictic (water turns over more than twice a year), well oxygenated, and contains excessive nutrients (eutrophic) because of fertilizer runoff from the neighboring farms and nurseries.

A perch-like fish called Oreochromis aureus was introduced from Africa, while a sardine like Topote, and the snail Tegogolo are the most common catches.

[1] The high rate of endemicity suggests that Lake Catemaco has been biogeographically isolated for some time, possibly since its origin up to 2 million years ago.

Blue tilapia (Oreochromis aureus), a perch-like fish, was introduced from Africa, while a sardine-like Topote, and the snail Tegogolo are the most common catches.