At 300 feet tall and 1,150 feet long, the Llyn Brianne Dam is the tallest dam in the UK. To call paddling down it in a kayak “death-defying” might just be an understatement. But that’s exactly what a group of paddlers did, launching themselves down a spillway, traveling at speeds upwards of 40 miles per hour. To give you a feel of just how crazy that is, watch this video:

Check out more photos at the Daily Mail Online, and read this BBC article which reports that after the pictures were published, Welsh Water condemned the activities.