Mamula Island is one of the most unique locations on this list. A hotel surrounded on all sides by the azure waters of the Adriatic Sea, it was once a 19th-century fortress, before becoming an Italian prison camp in World War II.
Shaking off its previous identity, Mamula has now been transformed into a stunning, secluded resort, complete with 32 rooms, a spa, a private beach, three pools, three restaurants and four bars, so you quite literally never need to leave. In their own words, everything at Mamula is 'designed to give you time to rest, move, make, share and dance, so you can reconnect with what you love'. Now that’s a mission to get behind.