Agiapuk River (also Agee-ee-puk, Ageepuk, Agiopuk, Ahgeeapuk) is a waterway on the Seward Peninsula in the U.S. state of Alaska.

The Agiapuk, flowing into Imuruk Basin from the north, drains an area of from 800 by 1,000 square miles (2,100 km2 × 2,600 km2) in the center of Seward Peninsula.

Below the forks, the Agiapuk makes many meanders on a broad flood plain, from which the upland rises by gentle slopes to flat-topped hills with elevations of 600–800 feet (180–240 m).

[4] The western branch occupies a broad depression which for about 20 miles (32 km) extends parallel with Grantley Harbor and Port Clarence, from which it is separated by an upland of about 1,000 feet (300 m) elevation.

The main part of the Agiapuk emerges from a comparatively narrow valley in these mountains into this depressed area.