An alpine lake is a lake at a high altitude in a mountainous zone, usually near or above the tree line, with extended periods of ice cover. These lakes are commonly formed from glacial activity (either current or in the past) but can also be formed from geological processes such as volcanic activity or landslides. Many alpine lakes that are fed from glacial melt have the characteristic bright turquoise or green color as a result of glacial flour, suspended minerals derived from a glacier scouring the bedrock. When active glaciers are not supplying water to the lake, such as a majority of alpine lakes of the Rocky Mountains in the U.S., the lakes may still be bright blue due to the lack of algae growth resulting from cold temperatures, lack of nutrient run-off from surrounding land, and lack of sediment input. The coloration and mountain locations of alpine lakes attract lots of recreational activity. Alpine lakes are some of the most abundant types of lakes on Earth. In the Swiss Alps alone, there are nearly 1,000 alpine lakes, most of which formed after the Little Ice Age. As global temperatures continue to rise, more alpine lakes will be formed as glaciers recede...