Glacier Bay National Park has 3.3 million acres of rugged mountains, dynamic glaciers, temperate rainforest, wild coastlines and deep sheltered fjords. The entire aquatic area was covered by ice as recently as 1794 and has retreated 65 miles since then. Wildlife in Glacier Bay includes both brown and black bear species, timber wolf, coyote, moose, black-tailed deer, red fox species, porcupine, marmot, beaver, Canadian lynx, two species of otter, mink, wolverine, and mountain goat. Birds that nest in this park include the bald eagle, golden eagle, five species of woodpecker, two species of hummingbird, raven, four species of falcon, six species of hawk, osprey, and ten species of owl. Marine mammal species that swim offshore are the sea otter, harbor seal, Steller sea lion, harbor porpoise, orca, minke whale, and humpback whale.
Glacier Bay contains a very complicated oceanographic system within a relatively small area. This complexity is one of the reasons why such an unusual variety of marine life is found here. The bay is a network of large, U-shaped valleys that, once, were filled by glaciers but now are flooded by the ocean and fed by streams and rivers. As the glaciers retreated, the ocean invaded the bay, creating a wide array of underwater environments, often with overlapping biological communities. These communities are part of a huge, complex and extremely productive marine food web, which is affected by the nutrients available, the water temperature and its salinity, and the topography of the ocean floor.
The bulk of this marine productivity is driven by countless billions of tiny plant-like creatures – called phytoplankton – that float suspended in a shallow band of water mainly in the Middle Bay where sunlight can penetrate. The phytoplankton are too small to be seen with the naked eye. Glacier Bay supports incredibly dense populations of phytoplankton that last throughout the spring, summer, and fall.