From Bulbapedia, the community-driven Pokémon encyclopedia.
are large bodies of fresh water that are found in the Pokémon world
. They tend to be home to a vast variety of Pokémon, mainly Water
types, as well as several others that live on the water's edge.
Lakes were not present in the main series games until Generation II, which introduced the Lake of Rage in northern Johto. Lakes aren't very common in the main series games, and have mainly appeared in spin-offs or the anime. Only five Lakes have appeared in the main series so far, with the majority (four) of them appearing in Sinnoh. All lakes require the use of Surf in order to be explored fully.
List of lakes in the Pokémon world