The website Switchback Travel has published a list over the Top 10 Adventure Destinations for 2013. Iceland is number one on that list. Three of the destinations—Iceland, Brazil, and Slovenia - were voted in by a poll taken by hundreds of adventure enthusiasts.
Switchback Travel has the following entry about Iceland:
Iceland beckons the adventure traveler, a dramatic and storied island of active volcanoes, steaming geysers, glaciers, thundering waterfalls, and deep fjords. The country landed on the travel map years ago when airlines starting offering free stopovers on the way to mainland Europe. Nowadays, Reykjavik is hip and increasingly cosmopolitan, but within driving distance from the capital city are wide-open spaces and wild Icelandic terrain.
Best time to visit Iceland: June–September for summer activities; January–March for winter activities and northern lights.