Fodor's Expert Review Askja Caldera

A large caldera in the center of a volcanic system with many fissures, Askja is one of the most stunning sights in all of Iceland. Although it has a history stretching back 700,000 years, the topography seen today—the pristine blue Öskjuvatn lake and Víti crater—is the result of a massive 1875 volcanic episode that produced more ash than any other in Iceland's history. It blanketed 3,861 square miles, wiping out livestock and forcing many to migrate to North America. The hike to Öskjuvatn lake and Víti crater is around 3 km (2 miles) from the Vikraborgir car park, where you'll also find well-maintained toilet facilities.