Dettifoss / Selfoss
is a waterfall in Vatnajökull National Park in Northeast Iceland, and is reputed to be the most powerful waterfall in Europe.
The water comes from the nearby Vatnajökull glacier, whose sediment-rich runoff colors the water a greyish white. The superlative of “most powerful” comes from its water flow times its fall distance. The water of the wide Jökulsá á Fjöllum river falls for more than 144 feet, causing a massive, crashing spray. The Norwegian cascade Sarpefossen has a greater average water flow, but only with about half the height of Dettifoss.