HST-2, formerly named USNS Puerto Rico and Alakai, is a vessel owned by the United States Navy Military Sealift Command.

The design of the Spearhead-class expeditionary fast transport is similar to the two high-speed ferries operated by Hawaii Superferry, both built by Austal USA.

[1] Like her sister ship USNS Guam (formerly Huakai), the vessel features environmentally friendly technologies including non-toxic bottom paint, zero wastewater discharge and clean diesel engines.

On March 17, 2009, after about 11 months in service, the Hawaii Supreme Court ruled that the legislation permitting Alakai to operate without an environmental review was unconstitutional.

[7] In January 2010, the United States Maritime Administration announced that Huakai and Alakai would be used to assist with relief in the 2010 Haiti earthquake.

[11] On January 27, 2012, the U.S. Department of Transportation's Maritime Administration transferred two high speed vessels, Huakai and Alakai, to the U.S. Navy under the Defense Authorization Act of 2012.

[14] Guam was modified to replace the chartered Westpac Express in Okinawa in March 2013, and Puerto Rico remained laid up until 2016.

On August 19, 2012, HST-2 (then USNS Puerto Rico) was towed from Norfolk, Virginia to Philadelphia, to keep it safe from hurricanes while future uses for the vessel were being evaluated.

[22][23] Service along this new route was originally expected to begin in summer 2019, but was delayed due to construction work at the Bar Harbor marina.