Strokkur (Icelandic for "churn") is a fountain geyser in the geothermal area beside the Hvítá River in Iceland in the southwest part of the country, east of Reykjavik. It is one of Iceland's most famous geysers, erupting about every 4-8 minutes 15 - 20 m high, sometimes up to 40 m high.
Strokkur is part of Haukadalur geothermal area, where are located various other geothermal features: mud pools, fumaroles, algal deposits, and other geysers beside and around it, such as Geysir.
Strokkur was first mentioned in 1789, after an earthquake unblocked the conduit of the geyser. Its activity fluctuated in 19th century, in 1815 its height was estimated to be even 60 m. It continued to erupt until the turn of 20th century, when another earthquake blocked the conduit again. In 1963, upon the advice of Geysir Committee locals cleaned out the blocked conduit through the bottom of the basin, and the geyser has been regularly erupting ever since.
Geysir sometimes known as The Great Geysir, was the first geyser described in a printed source and the first known to modern Europeans. The English word geyser (a spouting hot spring) derives from Geysir. The name Geysir itself is derived from the Icelandic verb geysa, "to gush", the verb from Old Norse. Geysir lies in the Haukadalur valley on the slopes of Laugarfjall hill which is also the home to Strokkur geyser about 50 metres south.