Its water enters the Atlantic Ocean on the coast of Maine by passing through the Magalloway, Androscoggin, and Kennebec rivers.

The Dead Diamond River is formed in the township of Atkinson and Gilmanton Academy Grant, New Hampshire by the juncture of the West Branch and the East Branch.

The Dead Diamond heads south through logging country, and the Little Dead Diamond River joins from the west at Hell Gate, a set of rapids, just before the Dead Diamond enters the Dartmouth College Grant.

The Swift Diamond River is a significant tributary which joins the Dead Diamond shortly upstream of the Magalloway.

This article related to a river in New Hampshire is a stub.