Twenty-three personnel were quickly saved, but three marines remained missing despite an air and sea search.
Valerie Cross, the Marine's mother, said, "we have so many awesome memories, but to know that we will never make any more with him is unbearable".
"He would sacrifice himself in a minute to make sure that his fellow service members were safe", Cross said.
Search crews suspended the rescue operation on Sunday and notified the families of those presumed dead in the wreck.
The Pentagon has not yet identified the third missing Marine. The ship's small boats and other aircraft immediately responded, the statement said.
The MV-22 Osprey had taken off from the USS Bonhomme Richard, an amphibious assault ship. The aircraft was found in Shoalwater Bay, off Queensland state.More news: Tottenham boss Mauricio Pochettino scores wonder goal in training
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The aircraft was in Australia for a joint military training exercise held by the USA and Australia last month in Shoalwater Bay in Queensland state. According to initial reports, the aircraft was on a landing approach to USS Green Bay during a training exercise when it crashed into the Pacific.
The tilt-rotor aircraft looks like a conventional plane, but can take off vertically without a runway with the help of its helicopter-like rotor blades. They have been involved in a series of high-profile crashes in recent years.
"Our thoughts are with all those affected by this tragic event and the Australian Government stands ready to support the USA further in any way we can", she said in a statement.
A squadron of Ospreys is based at the Marines' Futenma base on the southern Japanese island of Okinawa.
Three MV-22B Osprey tiltrotor aircrafts flying in formation above the Pacific Ocean off the coast of Sydney, Australia, on June 29.
Most recently, an Osprey crashed in January during a special operations raid on al-Qaida in the Arabian Peninsula in Yemen, leaving two servicemembers injured.