This is very interesting.
Apparently it defied the "conventional scientific wisdom" and wasn't believed, until now, when they have irrefutable proof.
I wonder what is causing them.
One possible cause is underwater earthquakes. Gasses could cause pressures. Large, deep underwater caves could cause periodic pressures as the water streams around inside them at different lunar cycles. And God-knows-what.
"Wonder what's causing them.."
I recall an article in Reader's Digest about 30 years ago..
A cadet training vessel, a sailing ship, was capsized at sea by what was believed to be a rogue wave..
The theory has been around a long time that it is "convergence", that waves can meet, and add their strength together..
With the proper conditions, the additive affects create these big boomers..
Another article I read on this subject noted the large waves that precede hurricanes, and pointed out that ocean currents and even weather fronts can contribute to abnormally large waves.
Still plenty to learn about the world we live in, let alone the universe..
Normal waves in the ocean are caused by when wind blows across the water's surface. The wave height is determined by wind speed, fetch, duration, and the water's depth.
Here is a wave machine. Play with it to see how high you can make a wave.
http://www.pbs.org/wnet/savageseas/multimedia/wavemachine.html