wow airlines ftw first classAutoplayShow ThumbnailsShow CaptionsLast SlideNext SlideThis year marks the 100th anniversary of the National Park Service, and there are plenty of commemorations planned at the 407 national parks. Emerald Pool hot spring is one of Yellowstone National Park"s 10,000 or so geysers, mudpots, steamvents and hot springs.(Photo: Karen Bleier, AFP/Getty Images)2015 was a tumultuous year in which world...