The Blackwater River is a 3.1-mile-long (5.0 km) tidal inlet in northeastern Massachusetts and southeastern New Hampshire in the United States.

Heading north, the river quickly enters Seabrook, New Hampshire and continues to flow through salt marsh until it reaches Hampton Harbor, northwest of Seabrook Beach, where it joins the Hampton River.

This article related to a river in Massachusetts is a stub.

You can help Wikipedia by expanding it.This Essex County, Massachusetts geography–related article is a stub.

You can help Wikipedia by expanding it.This article related to a river in New Hampshire is a stub.