Port Clarence Bay is a waterway in the U.S. state of Alaska. It has the only harbor and safe anchorage for large vessels in Seward Peninsula. The bay is located 25 miles southeast of York. It is a large body of comparatively deep water, nearly circular in outline, and cut off from the sea by a long, low sand spit, which terminates in at the entrance to the bay. Along the north side of Port Clarence Bay, there is a shallow lagoon, separated from the bay by a narrow sand spit. This lagoon extends several miles west of the entrance to Port Clarence. The hamlet of Port Clarence, Alaska is situated on the bay.