The large aircraft was on its approach to a marine base when it landed in Kaneohe Bay.

Nine people, including three pilots and six crew members, were on board at the time and all evacuated the plane, which is about 130ft (40m) long.

None were injured, as investigators try to establish the cause of last Monday's incident near Marine Corps Base Hawaii.

Weather conditions were cloudy and rainy at the time, with visibility about one mile, said a meteorologist.

The data recorder was retrieved by sailors from a diving and salvage unit on Thursday.

The P-8A plane is still in the water as the navy continues to work out how to remove it.

Kaneohe Bay is home to coral reefs and is a breeding ground for hammerhead sharks.

Residents are worried about possible coral reef damage and other potential harm from fuel or other chemicals in the area, which is about 1.5 miles (2.4km) from an ancient fishing point.

Containment booms have been placed around the aircraft as well as absorbent materials, and the area is being monitored by specialists 24 hours a day.

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About 9,300 military personnel and 5,100 family members are housed on the base, which is around 10 miles from Honolulu on Oahu.

The P-8A, made by Boeing, is often used to search for submarines and for reconnaissance and intelligence gathering.

The plane belongs to the Skinny Dragons of Patrol Squadron 4, stationed at Whidbey Island in Washington state.

Another crew from the same state, the VP-40 Fighting Marlins, arrived in Hawaii on Thursday to assume homeland defence coverage, the navy said.