High-speed Sea Service or Stena HSS was a class of high-speed craft developed by and originally operated by Stena Line on European international ferry routes. The HSS 1500 had an in-service speed of 40 knots (75 km/h).
Several patents were registered to Stena Line in the development of the HSS, and four vessels were completed between 1996 and 1997. Stena Explorer, Stena Voyager and Stena Discovery were built to operate around the British Isles with Stena Carisma built for Scandinavian use. The newest of the craft was renamed HSS Discovery after being sold to a ferry company in Venezuela during 2009.
Currently, none of the four craft originally commissioned by Stena Line operate. Stena Explorer was the last of the vessels to be retired in 2015 when Stena Line cancelled the fast ferry service between Holyhead, Wales and Dún Laoghaire, Ireland. As of March 2015, three of the vessels are laid up (Stena Carisma in Gothenburg, Sweden,HSS Discovery near Willemstad, Curaçao and Stena Explorer in Holyhead, Wales) while in 2013 Stena Voyager (on the Belfast-Stranraer route between 1996 and 2011) was sent to Landskrona, Sweden to be scrapped.
Three larger vessels were purchased, each capable of transporting up to 1,520 passengers at a time:
Two HSS 900 vessels were originally ordered, however following bankruptcy of the shipyard where they were constructed, the second one was scrapped at only 30% complete. This left only one that entered service:
Fuel Heavy oil fuel IF-100
Until 2011, two identical 1500 passenger versions were in operation on routes across the Irish Sea, whilst a smaller, 900 passenger version operated a route across the Kattegat. In 2011, Stena Voyager was withdrawn from service on the Belfast-Stranraer route to be replaced by two chartered conventional ferries, MS Stena Superfast VII and MS Stena Superfast VIII. In 2015, Stena Explorer ceased to operate service between Dún Laoighaire and Holyhead.