HST-2, formerly named USNS Puerto Rico and Alakai, is a vessel owned by the United States Navy Military Sealift Command. She was originally Hawaii Superferry's first high-speed ferry. The vessel was later chartered by Bay Ferries Limited to operate a ferry service between Maine and Yarmouth, Nova Scotia.

Hawaii Superferry was a Hawaii-based transportation company that provided passenger and vehicle transportation between Honolulu Harbor on the island of Oʻahu and Kahului Harbor on Maui. Legal issues over environmental impact statements and protests from residents of Maui and Kauaʻi temporarily delayed the implementation of service, but service between Oʻahu and Maui began in December 2007. The company had hoped to return service to Nawiliwili Harbor on Kauaʻi and additionally planned to eventually provide service to Kawaihae Harbor on the Big Island.