Lake Nicaragua or Lake Cocibolca is a fresh-water lake in Nicaragua. With an area of 8624 km², it is the second largest lake in Latin America, only slightly smaller than Lake Titicaca.

The Nicaraguans call it "the Sweet Sea". In fact, it has everything it needs to be a sea except that the water is not salty. Like any other sea, one cannot see from one shore to the other, and it has waves and archipelagos of islands, such as Ometepe and the Solentiname Islands, along with the only fresh-water sharks in the world. It has also built a reputation of having periodic, powerful, and impassable storms.

The lake is connected with the Caribbean Sea by the navigable San Juan River , historically making the lakeside city of Granada, Nicaragua an Atlantic port. The lake even had a history of Caribbean pirates. However, despite draining into the Caribbean Sea, the Pacific Ocean is near enough to be easily seen from the mountains on the lake's Island of Ometepe. Before construction of the Panama Canal, a stagecoach line connected the lake with the Pacific across the low hills of this narrow isthmus. Plans were made to take advantage of this route to build an interoceanic canal, the Nicaragua Canal, but the Panama Canal was built instead. In order to quell competition with the Panama Canal, the U.S. secured all rights to a canal along this route in the Bryan-Chamorro Treaty of 1916. However, the idea of another canal in Nicaragua still periodically resurfaces.