1. Mendenhall Glacier Caves, Alaska
AER Wilmington DE / Flickr: [email protected] / Creative Commons

AER Wilmington DE / Flickr: [email protected] / Creative Commons

Sergey Yechikov / shutterstock.com
In Mendenhall Valley of Juneau stands this 12-mile glacier that is home to some incredibly surreal ice caves. If you follow the West Glacier trail, you can get a chance to see these whimsical ice clouds for yourself.