First designated as a national monument in 1925, Glacier Bay National Park and Preserve was expanded to 3,283,246 acres (1,328,700 hectares) by ANILCA in 1980. This Act also designated 2.77 million acres of marine and terrestrial wilderness within the park.
Glacier Bay National Park and Preserve is a coastal, mountainous, wilderness landscape that includes the fourth-largest area of glacial ice on Earth. It protects and preserves extensive icefields, alpine glaciers, and tidewater glaciers that emanate from mountain ranges rising abruptly from the coast. A long history of glacial and tectonic activity along an active plate boundary has produced a complicated and dynamic geography and geology. A great diversity of bedrock types, terrain, and local climates has allowed the development of myriad habitat types in terrestrial, freshwater, and marine environments.