Rogue wave holes

now-b1594826-4da8-43c7-83fd-511cdae7f4da-1210-680I have long been fascinated by rogue waves, finding them to be the stuff of nightmares (literally; as a child I had recurring dreams about being in the path of one). Well, now it appears there are rogue troughs as well:

‘Rogue waves in the ocean can take two forms. One form is an elevated wall of water that appears and disappears locally. Another form is a deep hole between the two crests on the surface of water. The latter one can be considered as an inverted profile of the former. For holes, the depth from crest to trough can reach more than twice the significant wave height. That allows us to consider them as rogue events. The existence of rogue holes follow from theoretical analysis but has never been proven experimentally. Here, we present the results confirming the existence of rogue wave holes on the water surface observed in a water wave tank …’

Source: Journal of Geophysical Research: Oceans