Toolik Lake (TOOK) is an aquatic NEON field site located in the northern foothills of Alaska’s Brooks Range in a 63.7 km2 (15,700 acre) watershed. The lake is one of the largest in the area and is part of a lake district consisting of numerous kettle lakes formed by glaciers. These lakes and their outflows, along with runoff from snowmelt and rain, provide Toolik Lake with its water supply. Next to the lake is the Toolik Field Station, operated and managed by the Institute of Arctic Biology at the University of Alaska Fairbanks with cooperative agreement support from the Division of Polar Programs, Directorate for Geosciences at the National Science Foundation. TOOK is part of the NEON Tundra Domain (D18), which includes the northern and western parts of Alaska. D18 hosts three other NEON field sites in Alaska: one aquatic and two terrestrial. TOOK is colocated with the TOOL terrestrial site and near the Oksrukuyik Creek (OKSR) aquatic site.