Russian surfer Andrey Karr has performed a daring act, walking on a tightrope suspended some 15 meters above terrifying waves in Nazare, Portugal. /VCG Photo

Monstrous waves crashed on a nearby rock, distracting Karr, who lost balance a few times while in midair. /VCG Photo

The cable, on which the surfer was walking, is about 30 meters long and 15 meters high. /VCG Photo

The idea of walking above the Atlantic Ocean came to Karr in 2015, when he was inspired to challenge himself while watching the sunset from a lighthouse. /VCG Photo