Meet your guide and group in central Reykjavik, board the climate-controlled coach, and embark on the Golden Circle tour of Iceland's most remarkable natural landmarks. Along the way, learn about the history, ecology, and geology of the area from your local guide.  Stop at the Geysir geothermal area, home to the Strokkur geyser, which erupts with a 98-foot (30-meter) column of boiling water every few minutes. Continue to Gullfoss, one of Iceland's most impressive waterfalls, where the Hvítá River cascades into a 105-foot (32-meter) crevasse.  In Thingvellir National Park (Þingvellir), see the fields of verdant moss and the gash in the earth where the Eurasian and American tectonic plates are pulling apart.  Visit the Friðheimar greenhouse, where organic produce is grown using the power of the earth's geothermal heat. Learn about the growing process and taste some of the fruits of the farmers' labor.