Excelsior Glacier flows south for about 8 miles (13 km) from the Sargent Icefield on the Kenai Peninsula to its terminus at Big Johnstone Lake, formerly called Excelsior Lake, about 28 miles (45 km) west-southwest of Chenega Bay and 26 miles (42 km) southeast of Seward, Alaska. Big Johnstone Lake is currently about 6 miles (10 km) long and is drained by the Big Johnstone River that flows about 1.3 miles (2.1 km) to Johnstone Bay on Blying Sound in the Gulf of Alaska. The Sargent Icefield is located on the eastern portion of the Kenai Peninsula and extends south from Port Nellie Juan to the Gulf of Alaska, and bordering the west coast of Prince William Sound. The ice field has numerous outflow glaciers, the largest include Chenega, Princeton, Tiger, Bainbridge, Excelsior, and Ellsworth Glaciers. The icefield was named in 1952 by the U.S. Geological Survey for Rufus Harvey Sargent, a cartographer and author who did extensive exploring and mapping on the Kenai Peninsula from 1901 to 1936. At that time, Alaska was a mostly unexplored frontier, and Sargent introduced the use of photogrammetry and aerial surveys. Johnstone Bay is about 7 miles (11 km) across, on the southeast coast of the Kenai Peninsula between Cape Junken and Pinnacle Rock. It was named after James Johnstone, a British naval officer and explorer noted for having served as sailing master of the armed tender HMS Chatham and later acting lieutenant during George Vancouver‘s 1791–1795 expedition to the Pacific Northwest.

In 1909, the name Excelsior was locally used for this glacier. The word ‘Excelsior‘ is Latin and means ‘onward and upward’, and was made popular by a short poem written in 1841 by American poet Henry Wadsworth Longfellow. On July 11, 1909, a U.S. Geological Survey team led by U.S. Grant and D.F. Higgins passed the glacier when the terminus was within half a mile of the sea, ending on a low flat moraine of gravel. Patches of bare vegetation indicated that the glacier was retreating and had been considerably larger within a few years earlier when its terminus may have reached the sea. In 1941, Excelsior Lake was in the initial stages of development about 5 miles (8 km) north of Johnstone Bay. In 1994 the glacier was 13 miles (21 km) long and had retreated 3.4 miles (5.5 km) from the gravel moraine, and by 2001 the glacier had retreated 2,625 feet (800 m) from the 1994 position. In 2011, the glacier had retreated 7,218-8,202 feet (2200-2500 m), depending on where on the front the measurement is made, and large icebergs in Big Johnstone Lake indicated active calving. In 2018, the snowline was at 3,035 feet (925 m) leaving an insufficient accumulation zone to support the existing glacier mass, and Big Johnstone Lake had expanded to a length of 6.3 miles (10.2 km). The principal ice stream had fully separated into a western and eastern tributary, now called Roan Glacier at the head of Big Johnstone Lake. The lake was nearing its maximum size as the glacier surface slope had steepened within 0.6 miles (1 km) of the current terminus, indicating a substantial increase in elevation of the glacier base. In 2018, the west tributary, which is still called Excelsior Glacier, had lost about 30% of its length in 24 years.

The flat gravel moraine where Excelsior Glacier once terminated gradually became vegetated and one of the few places along this rugged coast where people could live. In 1959, the Alaska Statehood Act allowed for the state to make a land selection of about 105 million acres (42,492,030 ha) from federal lands. In 1971, the Alaska Native Claims Settlement Act was signed into law by President Richard Nixon and was intended to resolve long-standing issues surrounding aboriginal land claims in Alaska, as well as to stimulate economic development by granting the State of Alaska the right to select lands held by the federal government. One of the selections made by the state was most of the coastal lands fringing Blying Sound including Johnstone Bay. In 1979, the state Department of Natural Resources started the Remote Parcel Program which was a land disposal program that allowed Alaska residents the opportunity to stake a claim on state-owned lands. In March 1984, the lands along Blying Sound were opened to the last Remote Parcel Program, offering land parcels of 5 acres (2 ha) to the first people to arrive and stake out their land claim. This created a land rush of over 1,000 Alaska residents and caused hundreds of people to risk their lives attempting to reach this rugged inhospitable coastline in winter. A number departed from Seward in small boats, and after rounding Cape Resurrection were exposed to winds of 40 knots (74 kph) and seas of 10-15 feet (3-4 m). Others flew in with air taxis or private aircraft to attempt landing on the few sandy beaches. About 30 parcels between Johnstone Bay and Big Johnstone Lake were successfully staked and claimed over a three-week period, but the U.S. Coast Guard later found an overturned skiff in the Gulf of Alaska, and an air taxi pilot found an overturned canoe in Big Johnstone Lake where two men had drowned. Read more here and here. Explore more of Johnstone Bay here: