A principal tributary of the Ozette River, the Big River originates in the northwestern Olympic Mountains and empties into the Ozette Lake.

[2] The Big River originates in the northwestern portion of Olympic Peninsula and flows generally south and west.

The Big River flows south, collects the tributary Boe Creek, then flows southwest by the small town of Royal.

It collects Solberg Creek, Trout Creek, and Durham Creek before entering Olympic National Park and emptying into Swan Bay, part of Ozette Lake.

The lake's outlet, the Ozette River, empties into the Pacific Ocean.