Follow the path to where a circle of people is usually waiting in anticipation. They are here to see this magnificent geyser spurt water up to 40m in the air. It reliably erupts every five to 10 minutes (usually 15m to 20m), so make sure you are on the right side of it unless you want to get wet. It sits near the famous Great Geysir, which can blow boiling water some 70m in the air (but has been quiet for the past few years).
Strokkur, like all hot geysers, is caused by water meeting magma-heated rock, then boiling and erupting under pressure.
