There's an underwater canyon off the coast of Nazaré, Portugal that creates some of the largest waves in the world, and that attracts the world's best surfers. A video from a couple of days ago shows a surfer riding a wave that's so big it's frightening.
( There's no word how it compares to some of the record-breaking waves that other surfers have ridden off the coast of Portugal, but the video is still amazing.)