This sub-tropical gem is the second-largest of the Islands, and the only one to be privately owned. Tresco has a little bit of everything, from dramatic rocky outcrops and romantic castles to secluded sandy beaches and, of course, the famous Abbey Gardens, which were established by Augustus Smith in the 1830s. This horticultural paradise now showcases 20,000 exotic species, many of which cannot be grown anywhere else in Britain.