Chapultepec Lake is an artificial formation that was built in 1962 over a filled-in mining site. In 2006, a 15 meter crack was found and the lake was temporarily closed. During this time, the carp and tilapia overpopulation problem was solved. To the surprise of the people cleaning the lake, axolotls (Ambystoma mexicanum), an endangered salamander endemic to Mexico, were also found. The largest lake has an area of almost 53,000 square meters, and the smallest lake is 14,400 square meters. You can find several species of ducks there, and you can do kayaking, rowing, and other activities.