Laguna Lachuá is a Karstic lake in Guatemala. It is located in the middle of a national park covered with tropical rain forest, northwest of Cobán, near the border between the departments of Alta Verapaz and El Quiché. The lake is near circular in shape and is probably a cenote or doline. The lake water has a slightly sulphurous smell, which may explain the origin of its name: "Lachuá" is derived from the Q'eqchi' words "li chu há" which means "the fetid water". The water contains a relatively high degree of calcite and tree branches fallen into the lake are quickly covered with a white calcite layer.
The Peyan river forms the principal water inflow and the Lachua river its main outflow.
According to officials responsible for the protection of the park border, there have been incidents of intrusion by individuals and families as well as severe cases of illegal wood chopping since 2005. Those who have dared to protest this were often intimidated and threatened. The whole area around the park has been subject to heavy deforestation for the last decades.
In 1976 an area of 145 km² around the lake (15°55′09″N 90°40′23″W / 15.919074°N 90.673084°W) was designated a national park. Laguna Lachuá and its buffer zone were also declared a Ramsar site in 2006.