Before the Hringvegur (the main ring road round the island) was built, people feared traversing the plains in front of the volcano because of the frequent jökulhlaups (glacial floods) and the deep rivers to be crossed, although the road is still vulnerable to major events. Especially dangerous was the glacial flood after the eruption of 1918 when the coastline was extended by 5 km (3.1 mi) by laharic flood deposits.
Mýrdalsjökull is an exceedingly wet location, receiving more than 10 metres of precipitation annually.