Zachariæ Isstrøm, Glacier in Northeast Greenland National Park, Greenland

Zachariæ Isstrøm is a glacier system in Northeast Greenland National Park that flows as a massive ice stream toward the Arctic Ocean. The ice moves through a complex network of channels and flows that form one of Greenland's major outlet glaciers.

Scientific observation of this glacier system began in the late 20th century and initially showed relatively stable conditions. Beginning in the early 2000s, accelerated movement became evident, linked to broader Arctic environmental changes.

The name was given by the Denmark expedition of 1906–08, which honoured the Danish naval officer Georg Hugh Robert Zachariæ (1850–1937); Isstrøm is Danish for ice stream. The glacier ends in Jøkel Bay, between Lambert Land and Nørreland, near the Achton Friis Islands.

The glacier ends in Jøkel Bay, south of Lambert Land and north of Nørreland, near the Achton Friis Islands, in a bay once packed with multi-year calf ice. It is a research site reached by air and icebreaker, not a destination with marked routes or facilities; fieldwork is timed around calving and sea-ice conditions.

This ice stream is notable for moving at speeds significantly faster than most other Greenland glaciers. This rapid movement has made it a key focus for researchers studying glacier behavior in a changing climate.