On our second day, we went on a day excursion for the famous Golden Circle.
The first stop is the Gullfoss waterfall area, which is really composed of two waterfalls. Part of the waterfall was frozen when we were there.
The second stop is the Geysir geothermal area, where you can see the original Geysir from which the word "Geyser" originated. It's not very active right now but you will also see Strokkur, a geyser that bubbles and erupts every five minutes, and the Blesi pool (above).
The last stop on the Golden Circle is the Þingvellir National Park. This is where the Eurasian and North-American tectonic plates meet and you can clearly see the rifts between the plates (you'll see two rifts as there is a no-man's land being created between the two plates that are several kilometres apart).