World Lake Day, designated by the UN General Assembly and first observed globally in 2025, falls on August 27. It raises awareness of threats to lakes and promotes their conservation, restoration and sustainable management. Lakes support freshwater supply, biodiversity, climate regulation, livelihoods and flood control, but face pollution, overuse of water, agricultural runoff, climate change and habitat loss. Lake Baikal is the deepest freshwater lake in the world, and Lake Superior the largest by surface area.