Rogue Waves Explained, from Pitt T. Maner III
1. "Understanding rogue ocean waves may be simple after all"
"You have to account for the nonlinearity of the ocean, which is manifested in the lack of symmetry between the crests and the troughs," said Fedele, who also has an appointment in Georgia Tech's School of Electrical and Computer Engineering. "These nonlinear effects can produce an enhancement of 15 to 20 percent in wave height, which adds onto the effects of constructive interference."
- And here is an article about the math of it all.
"Real world ocean rogue waves explained without the modulational instability"