The world’s strangest hotel rooms, from underwater villas to glass igloos

Forget gliding down a red carpet. The next time you treat yourself to a luxury stay, you may find yourself shimmying down rungs nailed into a cliffside, or climbing up a staircase wrapped around a tree trunk: welcome to the global boom in extreme accommodation. No longer content with checking into a luxury suite, today's been-there-done-that traveller is looking for something more memorable – an underwater villa, perhaps, or a glass igloo. "It's not enough to stay at a five-star hotel anymore," says Michael Londregan, managing director Asia-Pacific for Virtuoso, a global network of luxury travel advisers. "These products are capturing people's imagination. They are structuring their entire trip around these experiences."