Gullfoss

Seen on a tour of the Golden Circle, this massive two-stage waterfall plunges dramatically into a steep gorge. Walk along an easy pathway to see multiple vantage points.

Geysir

Visit this site of the original geyser, accounts of which date to 1294. Geysir is rarely active, but Strokkur, a nearby geyser, erupts with a 30 meter spout every five to ten minutes.

Grjótagjá Cave

A beautiful cave near Myvatn containing a hot spring. You can't swim in the water, but the cobalt pool is picturesque, and a scene from Game of Thrones was filmed here if you're a fan.