World Lake Day Date in the current year: August 27, 2025

Lakes are relatively large, stationary bodies of water surrounded by dry land, though they may be connected to the ocean via rivers. They are generally found in mountainous areas, depressed landforms, along the courses of mature rivers, or in underground caverns. Lakes account for nearly all of the world’s surface freshwater; however, some contain salt or brackish water. There are more than 117 million lakes on Earth, covering nearly 4% of its land surface.

The world’s largest lake by surface area is the Caspian Sea, a saltwater lake spanning Europe and Asia. Although it is traditionally referred to as a sea due to its size and saltwater composition, geographically, the Caspian Sea is a lake. The largest freshwater lake by surface area is Lake Michigan-Huron in North America. Lake Baikal in Siberia is the world’s deepest lake and the largest by volume of freshwater. It is also the oldest lake on Earth.

Lakes are one of the most vital natural resources on Earth. First and foremost, they are an important source of readily accessible freshwater, supporting drinking water supplies as well as industry and agriculture. Lakes also provide significant economic and recreational opportunities, supporting local communities through fishing, tourism, and other activities.

Lakes are crucial to maintaining biodiversity because they provide a habitat for countless species of fish and other animals, plants, and algae. They also help regulate the climate by storing carbon, absorbing floodwater, and cooling the planet.

Unfortunately, lakes around the world are facing many challenges due to climate change, pollution, and overuse. Solid waste, fertilizers, and other contaminants are the main sources of lake pollution. These contaminants are either dumped directly into lakes or flushed into them via rivers. Global warming exacerbates this problem by causing more frequent and intense floods. Climate change has also resulted in dramatic changes in lake water levels, as rising temperatures and changes in cloud cover increase evaporation rates.

If nothing is done about lake overuse, environmental pollution, and climate change, the ecosystem value of lakes is expected to drop by 20%, and water pollution could more than double by 2050. It is crucial to raise awareness and promote education about the essential role of lakes in supporting ecosystems, preserving biodiversity, combating climate change, and sustaining human livelihoods.

In order to preserve our world’s lakes and ensure they are available for future generations, it is necessary to take coordinated action. This is why the UN General Assembly established World Lake Day in December 2024. The main goal of this day is to reaffirm the importance of sustainable lake management and protection in order to conserve and restore our planet’s lakes, overcoming the environmental challenges that endanger their unique ecosystems and biodiversity.