The 1955 Hawaiian submarine eruption was a submarine eruption that occurred 90 km (56 mi) northeast of Necker Island on August 20, 1955. Steaming water, water discoloration and an eruption column took place during the eruption. A possible pumice raft was also witnessed. The eruption originated about 4 km (2.5 mi) below sea level from an unnamed submarine volcano. It is probably the westernmost historical eruption within the Hawaiian Islands. Another but less certain submarine eruption may have occurred 60 km (37 mi) northwest of Oahu on May 22, 1956.