These are two of the most visited attraction which are situated side by side in the Haukadalur Valley. Geysir is the oldest known geyser in the world and the word 'geyser' itself has been derived from Geysir. Geysir is the bigger of the two geysers. It can send up boiling water to a height of 60 meters where as water form Strokkur rise only up to 30 meters. However, eruptions from geysers are very infrequent and sometimes lay dormant for years. But Strokkur is far more reliable and has an eruption every 5 to 10 minutes. This has made Strokkur a more visited attraction of the two. Once can see the bubble forming and then slowly bursting out gushing the boiling water many meters in the air.