To the northwest, the fjord opens into the Lincoln Sea of the Arctic Ocean.

The fjord is named after arctic explorer George W. De Long.

De Long Fjord opens to the northwest east of Nansen Land and to the west of Weyprecht Fjord, separated from it by the island of Hazenland.

[1] Its mouth is located to the south of the Wild Sound and southeast of Luigi Amadeo Island and Cape Mohn, and south of Hanne Island.

Although the islands in the fjord, as well as the peninsula flanking it, are unglaciated, the sea in the area is permanently covered by ice.