Police from several countries had been tracking the boat since it left Ecuador in August, Radio Australia reported Friday.
Some 204 one-kilo blocks of cocaine police believe were destined for Australia were found aboard the 42-foot vessel JeReVe.
The U.S. Drug Enforcement Administration, as well as police agencies from Australia, Tonga and the Cook Islands had been monitoring the vessel. Contact was lost Oct. 5.
The yacht was found Nov. 5 washed up on the atoll of Luatafito, 10 nautical miles from the capital, the Australian Federal Police said.
The drugs were found in the hull of the vessel, the BBC reported.
Tongan police commissioner Grant O'Fee said the body has not yet been identified. While the cause of the death has not been determined, O'Fee said foul play was not believed to be involved.
Two people are believed to have been on the boat when it left Ecuador, police said.