SS Mauna Loa was a steam-powered cargo ship of the Matson Navigation Company that was sunk in the bombing of Darwin in February 1942.

[4][Note 2] In December 1925, West Conob was allocated to Swayne & Hoyt Lines for service to the east coast of South America.

[4] By mid-1926, West Conob was sailing for Swayne & Hoyt's American-Australian-Orient Line when the Los Angeles Times reported her steaming to New Zealand with 350,000 square feet (33,000 m2) of wallboard.

[14][15] In October 1927, the Los Angeles Times reported on the impending sale of West Conob and 18 other Swayne & Holt ships to a San Francisco financier.

[2] In March 1934, Matson began a new "sugar, molasses and pineapple service" from Hawaii to San Francisco, Los Angeles, and either Philadelphia or New York, employing Golden Eagle and three other cargo ships.

[18][Note 4] In May, after returning from New York on her first voyage in the new service, Golden Eagle entered drydock at Los Angeles for general repairs and repainting.

[20] Mauna Loa continued on the Hawaii–California–Philadelphia/New York service, occasionally making extra voyages from Los Angeles to Honolulu when dictated by cargo bookings.

[21] In August 1936, Mauna Loa diverted to respond to a distress call issued by the windjammer Pacific Queen some 700 nautical miles (1,300 km) southwest of Los Angeles.

[23][Note 5] Less than three weeks after Mauna Loa's charter, the Japanese Attack on Pearl Harbor propelled the United States into World War II.

Mauna Loa, sailing independently from the US, was diverted in the days after the Pearl Harbor attack to Sydney, Australia, arriving on December 29.

[24] Japanese forces advancing south from the Malayan Peninsula had reached Timor by mid-February thus breaching the Malay Barrier that had been a priority defense line.

[26] The American cruiser Houston and destroyer Peary, and the Australian sloops Swan and Warrego, led Mauna Loa and three other civilian ships out of Darwin Harbour at about 03:00 on 15 February heading for Koepang with relief intended for Timor.

[26][29][Note 7] The ships were spotted by a Japanese Kawanishi H6K "Mavis" four-engined flying boat that tailed the convoy at 10,000 feet (3,000 m).

[26] When Captain Albert H. Rooks of Houston requested air cover for the convoy,[30] a lone Curtiss P-40 responded and engaged the Mavis, with each plane managing to shoot down the other.

[31] At around 09:00 the next day, another Mavis began trailing the convoy and at 11:00, 36 land-based Mitsubishi Ki-21 "Sally" twin-engine bombers and ten seaplanes attacked in two waves.

[39] Military trucks, Bren Gun Carriers, a Harley-Davidson motorcycle, and many rounds of .303- and .50-caliber ammunition are among the pieces of Mauna Loa's cargo that still lie strewn about the wreck.