Antinous was a Design 1015 ship steam cargo ship built in 1919–1920 by Guy M. Standifer Construction Company of Vancouver for the United States Shipping Board as part of the wartime shipbuilding program of the Emergency Fleet Corporation (EFC) to restore the nation's Merchant Marine. The vessel was chiefly employed on the Gulf to Europe routes throughout her career. In September 1942, while on a passage to British Guiana to load her cargo, she was torpedoed and sunk by German submarines operating at the time in the Caribbean.

After the United States entry into World War I, a large shipbuilding program was undertaken to restore and enhance shipping capabilities both of the United States and their Allies. As part of this program, EFC placed orders with nation's shipyards for a large number of vessels of standard designs. Design 1015 cargo ship was a standard cargo freighter of approximately 9,400 tons deadweight designed by Moore Shipbuilding Co. and adopted by USSB.

Antinous was part of the order for 5 additional vessels placed by USSB with Guy M. Standifer Construction Co. on 30 September 1918. Due to overabundance of cargo ships being constructed and lack of tanker vessels being built, this contract was unilaterally suspended by USSB on 11 February 1919. After prolonged negotiations between G. M. Standifer Company and the Shipping Board about the amount of compensation, the Fleet Corporation formally cancelled the contract on 1 November 1919 and two days later the shipbuilder signed a new contract with Nafra Company, an affiliate of the newly formed Green Star Steamship Corporation, to construct five vessels nearly identical to those cancelled by USSB. Due to rapid expansion which involved acquisition of more than a dozen ships in a matter of several months, the ship operator incurred indebtedness of nearly US$40,000,000 running into financial problems and becoming delinquent on their payments in February 1920. After further negotiations, all five vessels were paid off by the EFC and allocated to Green Star Line to operate on their trade routes at the end of July 1920. Antinous was the fourth of these vessels and was launched on 22 June 1920 (yard number 14), with Mrs. Ellis Lewis Garretson of Tacoma, wife of the deputy Imperial Potentate of the Shriners, being the sponsor.

The ship had two main decks as well as forecastle and poop deck and was built on the Isherwood principle of longitudinal framing providing extra strength to the body of the vessel. The freighter had five main holds and also possessed all the modern machinery for quick loading and unloading of cargo from five large hatches, including ten winches and a large number of derricks. She was also equipped with wireless apparatus, had submarine signal system installed and had electrical lights installed along the decks.

As built, the ship was 401.4 feet (122.3 m) long (between perpendiculars) and 53.2 feet (16.2 m) abeam, a depth of 31.9 feet (9.7 m). Antinous was originally assessed at 6,094 GRT and 3,816 NRT and had deadweight tonnage of approximately 9,604. The vessel had a steel hull with double bottom throughout with exception of her machine compartment, and a single 2,500 ihp triple expansion steam engine, with cylinders of 24+1⁄2-inch (62 cm), 41+1⁄2-inch (105 cm) and 72-inch (180 cm) diameter with a 48-inch (120 cm) stroke, that drove a single screw propeller and moved the ship at up to 11 knots (13 mph; 20 km/h). The steam for the engine was supplied by three single-ended Scotch marine boilers fitted for oil fuel.

The sea trials were held on July 22 during which the steamer performed satisfactorily and was handed over to Green Star Line upon their completion.

Following delivery to her operator, Antinous sailed from Portland on 27 July 1920 to Prescott to load part cargo of lumber destined for United Kingdom. Over the next two weeks she visited various ports around the Puget Sound such as Bellingham, Mukilteo and Vancouver to complete her cargo of about 5,000,000 feet of railroad ties. She sailed on her maiden trip from Vancouver on August 14 bound for Southampton. However, on August 16 while travelling through the Strait of Juan de Fuca she suddenly developed a list to starboard side followed by a 10° list to her port side forcing her to call at Port Townsend on August 16 to rectify the problem. There she was ordered to discharge about 100,000 feet of ties from her deckload cargo reducing her total load down to 4,798,000 feet. The freighter then continued on via San Pedro and the Panama Canal to her destination. She departed England on October 25 and arrived at New York on November 8, thus successfully completing her maiden voyage. From New York the steamer proceeded to Norfolk where she took on board 7,689 tons of coal and departed for Le Havre on November 19. The steamer made one more trip to England with coal in 1921 before being allocated to the Waterman Steamship Corporation in December 1921 to serve on their trade routes from the Gulf Coast to England. In late February and early March 1922 the vessel took on a cargo of wheat at New Orleans, continued on to Pensacola where she embarked about 500,000 feet of lumber and 100 barrels of turpentine and then sailed for Mobile to finish loading. In the morning of 8 March 1922 while entering the Mobile Bay, Antinous and another USSB vessel, SS Bayou Chico, leaving Mobile collided just outside the river mouth. Bayou Chico had her port bow completely demolished and was taking on water fast and had to be beached in order to prevent sinking. Antinous was taken by a tug to a ship anchorage where she was examined and found to have only suffered minor damage to her bow. Despite the accident, Antinous managed to leave on her trip after loading the remainder of the cargo in Mobile.

Antinous continued to be operated by the Waterman Steamship Corp. for the next eight years transporting cargo from a variety of Southern ports of the United States such as Mobile, New Orleans, Pensacola and Gulfport to ports in the United Kingdom and Europe. During her earlier years of service the vast majority of cargo was routed to London and consisted mostly of lumber, cotton, gum rosin and related products. For example, in June 1924 she cleared from Mobile for England having on board 1,301,564 feet of lumber and 291,500 pounds of gum rosin.