Ariaú Amazon Towers Hotel, Manaus, Brazil

At the intersection of the Rio Negro and Ariaú Creek is Ariaú Amazon Towers Hotel, accessible only by boat and made up of a series of stilted wooden towers under the rainforest canopy. Monkeys, sloths and macaws live and play along the miles of catwalk between the towers, and at night the hotel leads alligator searches. During the day visitors can watch for pink dolphins in the Rio Negro and learn forest-survival skills. With so much to offer, it is no wonder that guests like Bill Gates and Prince Charles have stayed here. Rooms, from $540 (all-inclusive); 669 Leonardo Malcher Ave.; 888-462-7428; ariauamazontowers.com.