There are several other pools of hot, bubbling water at the same site, not to mention several hot springs scattered throughout Iceland. Iceland is a prime spot for geological activity. Due to Iceland's high level of volcanic activity, hot, boiling water is pushed up from below surface to produce geysers, or heat small bodies of water. This is very similar to Yellowstone National Park in Wyoming, USA. The park sits on a geologically active volcano spot.
Had I not already seen the geysers at Yellowstone as a kid, I'd probably find these in Iceland more impressive. The Geysir area is a bit too built up and developed for tourism for my liking. Regardless, it's still a must visit attraction in Iceland! It just wasn't one of my favorites.