The Cocoon was built by designers Bellemo & Cat as a lightweight structure with minimal impact on the surrounding environs, and was placed in such a way, that, from the inside, it appears the place is resting in the treetops. The Cocoon, which is located in Wye River, Victoria, can be rented for as little as $240 a night, but you'll have to bring your own period furnishings; the Cocoon's interior decorations are decidedly modern.

[Bellemo & Cat via Inhabitat]

The Aerohotel is the latest concept design by Russian architect Asadov. A system of supports anchored to the ground keep the structure aloft while creating the impression that it would fly away if it weren’t tethered. Docks can be placed around the supports for boats, but the design includes landing strips for zeppelins to increase the ethereal experience of your stay. Light filters into the rooms and public areas from all directions, and the center of the hotel would feature not only shops and cafes, but also hanging gardens.

Although the hotel is not currently in development, it has attracted a great deal of attention, especially from Arab investors. Because the Aerohotel support system requires very little subaquatic construction, it can be placed in any body of and does little to disrupt the environment below. As a result, it could prove a cost-efficient and environmentally friendly alternative to the man made islands that have proven so ecologically devastating.

[World Architecture News via Inhabitat]