(, Thing Fields) is a place in Bláskógabyggð in southwestern Iceland, near the peninsula of Reykjanes and the Hengill volcanic area. Þingvellir is a site of historical, cultural, and geological importance and is one of the most popular tourist destinations in Iceland. It is the site of a rift valley that marks the crest of the Mid-Atlantic Ridge. It is also home to Þingvallavatn, the largest natural lake in Iceland.