The US Navy has punished a sailor who was presumed to be lost at sea, prompting a massive search and rescue operation, but was later found hiding on board.

Petty Officer 3rd Class Peter Mims, a gas turbine systems technician on the USS Shiloh, was believed to have gone missing on June 8 while the Shiloh was conducting routine operations 180 miles east of Okinawa, Japan. His disappearance prompted a search involving both American and Japanese ships scouring 5,500 square miles of the Philippine Sea over a span of 50 hours.

Mims had, in fact, never left the ship and was eventually found by his shipmates hiding in an engineering space, officials said.

It's not clear why he hid or how long he was planning on hiding.

Mims disappeared before a naval proceeding known as an "Admiral's Mast," during which time he admitted his appearance was intentional and said he took "steps to avoid being found by other Shiloh sailors who were actively attempting to locate him," Lt. Paul Newell, a spokesman for the Navy's 7th Fleet, told CNN.

After the confession, Mims received a nonjudicial punishment "due to the seriousness of the incident and the impact it had on the entire strike group and our Japanese allies," Newell said.

Newell declined to say how exactly Mims was punished, but said the Navy is considering additional administrative discipline.

Rear Adm. Charles Williams, commander of the carrier strike group that includes the USS Shiloh, called Mims' discovery in June a relief to the Navy community.

"I am relieved that this sailor's family will not be joining the ranks of Gold Star Families that have sacrificed so much for our country," he said.

Newell said Mims' actions violated the Uniform Code of Military Justice's Article 86, abandoning watch, and Article 92, dereliction in the performance of duties.