Guided tour of the Nesjavellir geothermal power plant, the source of some of the geothermal energy used to heat Reykjavík and the surrounding area, followed by a drive around the shores of Thingvallavatn, Iceland’s largest lake, to Thingvellir, the historic site of the Old Icelandic Parliament. Today a national park, this priceless natural treasure, with its canyons, chasms, and river, is an adventure in itself. Further surprises await on the return trip to Reykjavík, including the massive explosion crater Kerid.