While there have been accounts of giant, freak or rogue waves in sailor’s stories for many centuries, the first measurement of such waves was not taken until 1995. It was then that the oil platform Draupner in the North Sea was hit by a rogue wave of 26 meters. Rogue or monster waves occur in open water where winds and currents and other circumstances cause the water to form a wave that is far larger than average. This is caused by different waves that travel at different speeds, making it possible for them to pile up and form one massive motion. They can occur even when the sea seems calm and quiet.The gif was created in a fairly small layout that appears almost innocent and soft, contrasting to the height and destructive power a monster wave can have.
Sources: Marklund, Mattias and Lennart Stenflo, “Exciting rogue waves”, Physics 2, (2009).