From Wired News:

If you want to study the rainforest, there is no better place to be than on top of it — literally. This pretzel-shaped structure on top of the Masoala National Park forest in Madagascar is called a canopy raft. Biologists use it to access the rainforest canopy, the upper layer of the forest.

These inflatable surfaces are lowered by a blimp and placed right on top of the trees, providing scientists with a working surface of 400 square metres of mesh strung between PVC hoops. “We just used to have ropes and climbing gear,” says canopy scientist Meg Lowman of the New College of Florida. “Now, a canopy raft mission costs about $1 million, involving about 50 people at the base camp and eight on the raft,” she says. “They last for days and everybody takes turns on one.”