Tracy Arm is a glaciated fjord in the Tracy Arm–Fords Terror Wilderness of Tongass National Forest, about 85 miles (137 km) northeast of Sitka and 42 miles (68 km) southeast of Juneau, Alaska. The Sawyer Glacier terminates at the head of the fjord, which trends generally southwest for 28 miles (45 km) to Holkham Bay. Tracy Arm was named in 1889 by Lieutenant Commander Henry B. Mansfield of the US Navy for Benjamin F. Tracy, a veteran of the American Civil War who served as Secretary of the Navy under President Benjamin Harrison from 1889–93. Mansfield succeeded Charles M. Thomas as commander of the Coast and Geodetic Survey steamer Carlile P. Patterson in the spring of 1889 and remained in command until succeeded by Edwin K. Moore on February 2, 1892. He conducted hydrographic surveys in the Alexander Archipelago and fjords of the Coast Mountains in Southeast Alaska during the seasons of 1889, 1890 and 1891.

Tracy Arm is the heart of the Tracy Arm–Fords Terror Wilderness, designated by Congress in 1980. The wilderness encompasses 653,179 acres (264,332 ha) and comprises two fjords: Tracy Arm and Endicott Arm. Both are over 30 miles (48 km) long, and one-fifth of their area is covered in ice. During the most recent glaciated period, both fjords were filled with active glaciers. Tracy Arm was once filled by the Sawyer Glacier, which has since receded about 30 miles (48 km). The fjord still contains considerable floating ice, ranging from small chunks a few inches (10 cm) across to pieces as large as a three-story building. The largest pieces commonly strand on an underwater moraine near Holkham Bay and gradually disintegrate into smaller pieces that drift and wash ashore on the mainland. Glacial gravel forms much of the shoreline substrate, and larger cobbles and boulders provide stable anchors for rockweed that can tolerate low salinities and cold air temperatures. A fringing salt marsh of sedges lines the shore, and a successional community of terrestrial grasses, alder and spruce has colonized the uplands, creating a mosaic of colors.

In the early morning of August 10, 2025, a landslide occurred in Tracy Arm, about 80 miles (130 km) south-southeast of Juneau, generating a tsunami in the fjord. The Alaska Earthquake Center first detected the event, noting seismic waves indicative of a landslide at about 5:30 am local time. Kayakers camped at the mouth of Tracy Arm on Harbor Island in Holkham Bay reported their gear being swept away by rushing water. Preliminary interpretation of photos taken by kayakers in the area indicates that the landslide generated a tsunami at least 100 feet (30 m) high at Sawyer Island, a small island located where the fjords containing South Sawyer and North Sawyer glaciers meet. The tsunami was also recorded on a NOAA coastal tide gauge in Juneau, some 80 miles away. The National Tsunami Warning Center reported a maximum wave height of 14 inches (36 cm) above the tide at the gauge, with waves continuing for hours. Landslides that fail into water bodies such as lakes, fjords and bays are relatively common in the steep, glaciated mountains of Alaska. The 1958 Lituya Bay landslide-generated tsunami had a peak runup of about 1,720 feet (524 m). In 2015, a large landslide in Taan Fjord generated a tsunami with runup directly across from the landslide of 633 feet (193 m). Most recently, in August 2024, a landslide produced a tsunami 56 feet (17 m) high in Pedersen Lagoon in Kenai Fjords National Park. Read more here and here. Explore more of Tracy Arm and Tracy Arm-Fords Terror Wilderness here: