While it is tricky to observe rogue waves directly, it is now possible to measure wave height from space
Rogue waves, towering at least twice as high as the other waves present, seem to appear at random. Their rarity makes them difficult to study, and for years they were considered a sailors’ myth. They are especially common off the east coast of Africa, making this a fruitful area for rogue wave research.
A key factor is the how the fast-running Agulhas current runs south and collides with ocean swells running north from the Southern Ocean. The current modifies the shape and height of the waves, tending to make them steeper and amplifying them.