Blue Glacier is a large glacier located to the north of Mount Olympus in the Olympic Mountains of Washington. The glacier covers an area of 1.7 sq mi (4.4 km2) and contains 580,000,000 cu ft (16,000,000 m3) of ice and snow in spite of its low terminus elevation. The glacier length has decreased from about 3.4 mi (5.5 km) in 1800 to 2.7 mi (4.3 km) in the year 2000. Just in the period from 1995 and 2006, Blue Glacier retreated 325 ft (99 m). Blue Glacier is also thinning as it retreats and between 1987 and 2009 the glacier lost 178 ft (54 m) of its depth near its terminus and between 32 and 48 ft (9.8 and 15 m) in the uppermost sections of the glacier known as the accumulation zone.
Starting at an elevation of 7,800 feet (2,380 m) near Mount Olympus's three summits, the Blue Glacier begins as a snow/ice field separated by arêtes. As the glacier flows north, it cascades down a steep slope and thus, the smooth ice turns into a chaotic icefall, replete with seracs and crevasses. After the ice passes the icefall, the glacier ends up in a valley and takes a left turn to the west. Another ice stream from a snowdome located to the northwest of Mount Olympus joins the Blue Glacier and together, the joined ice streams flow down to a cliff at 4,050 feet (1,234 m). On this steep, barren, rocky slope, the Blue Glacier terminates after dropping over 3,700 feet (1,130 m) in only 2.7 mi (4.3 km). The rocky cliff used to host a second icefall before the terminus of Blue Glacier retreated up the cliff.