This photograph of the Alaskan Peninsula, shot by an astronaut from the International Space Station (ISS), offers an oblique view of Katmai National Park. Many of the mountains are active volcanoes, part of the Aleutian Range, and several are topped by glaciers.

Just northwest of the coastal mountain range lies the Valley of Ten Thousand Smokes, a river valley that was buried by an eruption of Novarupta volcano in 1912. It was the largest volcanic eruption of the 20th Century.

Large quantities of hot ash and pumice were ejected during the eruption. The rain of hot debris buried the snow and glacial streams, immediately flashing them into steam. Those volcanic deposits remained hot for years afterwards and often converted subsequent precipitation and surface stream flows into steam, hence the name Valley of Ten Thousand Smokes. During the same eruption, the summit of Mount Katmai collapsed, forming a deep caldera that has filled with water as a crater lake.

Katmai National Park has multiple sediment-rich rivers that deliver freshwater to the ocean. These rivers and streams provide avenues for anadromous fish species, especially salmon, to migrate and spawn upstream in the park. The abundance of fish is important for some of Katmai's other residents: bald eagles and brown bears.