Mendenhall Ice Caves, Alaska
There aren’t many times or places where you can experience multiple stages of matter at once. This is the case for the Mendenhall Ice Caves in Alaska, where you get to experience the flowing water inside the glacier above you while standing on the ice of the same glacier below you. This wonder does require some work— having to physically kayak to the edge of ice and climb across the glacier itself. If you planned on visiting anything, this might be the one wonder to visit. It’s receding incredibly fast due to the global warming phenomenon.