The Nisqually Glacier is one of the larger glaciers on the southwestern face of Mount Rainier in the U.S. state of Washington. The glacier is one of the most easily viewed on the mountain, and is accessible from the Paradise visitor facilities in Mount Rainier National Park. The glacier has had periods of advance and retreat since 1850 when it was much more extensive. It is currently retreating. Measurements made at altitude show that glacier got thicker between 1994 and 1997, suggesting that it will probably begin advancing in the first decade of the 21st century. Nisqually Glacier is the source of the Nisqually River.