I don't know a thing about tsunamis, but at sea the wind causes extreme wave buildup. I've been at sea in a moderate storm, and when the bow of your ship plows under the water and the wave hits mount 51, and the resulting splash goes over your head while you're standing on the signal bridge, you know it's more than just a few inches.
Here is the expected wave height at different wind speeds:
http://www.peardrop.co.uk/beaufort.htm
Note the maximum listed in a hurricane - 16 meters. That's more than 50 feet.
As for the submerged sub being affected, again I don't know about being extremely deep, but I've read that at periscope depth conditions aren't much better than on the surface in a storm, and you need to be at least 100 feet down to start being comfortable.