USS Hilo (AGP-2) was a converted yacht that saw service as a motor torpedo boat tender in the United States Navy during World War II.

It was built with a laboratory as well as palatial quarters and was loaned and equipped by Johnson for the Johnson-Smithsonian Deep-Sea Expedition of 1933 that explored the Puerto Rico Trench.

[4][5] The gyroscope wheel itself weighed 88,000 pounds (40,000 kg) spun by a 210-horsepower Diesel-electric motor at 13,000 revolutions a minute and taking one and a half hours to reach that maximum speed.

[9] Johnson offered the use of the Caroline for scientific research including a 1932 archeological expedition to South America and Easter Island.

The first was to the Puerto Rico Trench embarking investigators from several disciplines and government agencies and institutions interested in oceanographic work.

[5] The ship arrived Pearl Harbor on 5 July 1942, and was immediately sent to Palmyra Island to tend to torpedo boat squadron 1B (consisting of PT-21, PT-23, PT-25, and PT-26).

Hilo remained in the vicinity fueling and providing supplies to the boats then under training until returning to Pearl Harbor again on 4 October.

[5][24] The ship remained at Funafuti until 25 November, tending torpedo boats and engaging in rescue operations as American forces prepared for the coming assault on the Gilberts and Marshalls.

On 12 November the Hilo and other units from Funafuti rescued Eddie Rickenbacker and the crewmen of a crashed B-17 after they were adrift at sea in rubber boats for 21-days.

Commencing operations soon after their arrival, Hilo's boats contributed to the hard-fought Buna-Gona campaign in New Guinea as allied forces began their return to the Philippines.

[5] In February 1943, Hilo explored the coast for a suitable advance PT boat base, and by the 28th had established one at Kana Kope.

The torpedo boats stationed there with Hilo soon had a chance to fight, as Japanese efforts to reinforce their Lae and Salamaua garrisons led to the Battle of the Bismarck Sea from 2–4 March.

[5] Commander, Motor Torpedo Boat Squadrons, 7th Fleet, shifted his flag to Cyrene on 16 January, and for the next nine months Hilo was occupied with passenger voyages to various islands, including Mios Woendi and the Palaus.

[5] The ship entered the Suisun Bay National Defense Reserve Fleet on 30 June 1946 and was sold on 6 November 1947 by the United States Maritime Commission to Pillsbury & Martingnoni, San Francisco, California.