Two Marines walking on the beach saw the man in the waters of Ourawan Bay, off the island's northeastern shore, about 9:00 p.m. local time Monday.
One of the Marines went into the water to attempt a rescue but lost sight of the man, according to Hiroshi Iwanaga, chief of the search and rescue division of the coast guard's Nakagusaku branch.
A search was launched, with patrol boats and a helicopter scanning the water throughout the night. However, the search was suspended Tuesday due to an approaching storm.
Iwanaga said the missing Marine's name could not be released. A cell phone and a pair of shoes were found on the beach, he added.
USMC officials confirmed to Stars and Stripes that a Marine was listed as missing.