Tsingy de Bemaraha National Park, Madagascar. Erosion has carved the land on this part of the African island into a remarkable stone forest. Much of the wildlife found in this area live nowhere else in the world. (Photo: Haja Rasambainarivo via Getty Images)
Kayak through the Apostle Islands, off the Wisconsin shore of Lake Superior. The group of 22 islands is riddled with caves, and during the winter visitors can see frozen waterfalls and icicle-filled chambers.