Crew with binoculars on cruise ship Safari Endeavour at the Margerie Glacier and Mount Fairweather in Glacier Bay National Park Alaska USA. Tarr inlet in Glacier Bay National Park. Margerie Glacier is a 21-mile-long (34 km) tide water glacier in Glacier Bay in Alaska and is part of the Glacier Bay National Park and Preserve. It begins on the south slope of Mount Root, at the Alaska-Canada border in the Fairweather Range, and flows southeast and northeast to Tarr Inlet. It was named for the famed French geographer and geologist Emmanuel de Margerie (1862–1953), who visited the Glacier Bay in 1913. It is an integral part of the Glacier Bay, which was declared a National Monument on February 26, 1925, a National Park and Wild Life Preserve on December 2, 1980, a UNESCO declared World Biosphere Reserve in 1986 and a World Heritage Site in 1992. While most of the tidewater and terrestrial glaciers in the Park are stated to be thinning and receding over the last several decades, Margerie Glacier is said to be stable and Johns Hopkins Glacier is stated to be advancing, on the eastern face of the Fairweather Range.