In 2010, a team of designers was asked to build a tree house in a yard without trees. The seemingly impossible task gave birth to the Tentsile, the portable "tree house" that can be set up in just 30 minutes, in just about any environment.
Whether you go with the 2, 5 or 8-man model, the Tentsile provides plenty of space, supported above the ground, safe from rising water and predators (if you're in a really wild spot). The team sees it as the ideal habitation for biological research groups who move through nature and want to travel light. They also note winter sports, wildlife filming, camping and military excursions as potential uses.
The Tentsile isn't shockingly light, but the two-man model weighs in at between 11 and 18 pounds, which isn't too heavy, either.