Deep lake

Deep lake is a tile in Factorio categorized as a decoration; it represents a deep-water terrain tile used to visually depict large bodies of water on the map and to define non-buildable or water-covered areas of terrain. As a tile, Deep lake is part of the game's terrain system and is used by the map generator and environment rendering to create lakes and water features; it behaves like other water tiles with respect to placement and entity interaction and is intended primarily for visual and terrain-shaping purposes rather than as a craftable item or building.