HONG KONG — Almost three years after Malaysia Airlines Flight 370 disappeared with 239 people on board, officials said on Tuesday that they had called off the underwater search for the plane, ensuring that one of the great aviation mysteries will remain unsolved for the foreseeable future.

The decision, which had been expected, indefinitely suspends an intensive deep-sea search in the southern Indian Ocean for remnants of the plane, a Boeing 777. The underwater search turned up no traces of the aircraft, although pieces of debris were found as far away as Tanzania.

Flight 370 disappeared on the way from Kuala Lumpur, the Malaysian capital, to Beijing on March 8, 2014, prompting the largest and costliest search in aviation history. Investigators determined that the plane veered off course and flew south for several hours, for reasons that remain unknown.

“Today the last search vessel has left the underwater search area,” the governments of Australia, China and Malaysia, the three countries that oversaw the search, said in a joint statement on Tuesday. “Malaysia Airlines Flight 370 has not been located in the 120,000-square-kilometer underwater search area in the southern Indian Ocean,” a zone of more than 46,000 square miles.