Of the hot springs in Iceland the Great Geysir and the Strokkur are the most famous. And it really is breath taking to see the hot water moving and then burst out into a fountain every seven minutes. The Strokkur is the most active but he was not really showing off when we where there.
What I also found just as interesting were the ordinary hot springs. They looked like poodles of water but at a closer look they were very deep and the water was boiling hot. Amazing. I held my hand about 50 cm above the spring and still felt the heat.