Another large eruption occurred on 21 May 2011. This time it was the Grímsvötn volcano, located under the thick ice of Europe's largest glacier, Vatnajökull. Grímsvötn is one of Iceland's most active volcanoes, and this eruption was much more powerful than the 2010 Eyjafjallajökull activity, with ash and lava hurled into the atmosphere, creating a large cloud.