One World Karadeniz (previously Stena Explorer) is a former high-speed ferry that operated Stena Line's Holyhead–Dún Laoghaire service between Great Britain and Ireland until 2014. It is a member of the HSS 1500 class of high-speed ferries introduced and developed by Stena Line from 1996 onwards. The HSS 1500 class vessels became the largest catamarans in service in the world.