We were on Vision of the Seas in the North Atlantic near Iceland in October 1998, and the seas were probably worse than that. The seas were over 40 feet for four days and at least 55 feet with 85 mile winds on the worst day.
With the stabilizers fully deployed and heading into the waves, on the 800 foot plus ship, the screw would come completely out of the water, stop, and then start again after the ship stern crashed back down.
The display on the television which shows the waves and lists the ocean conditions whowed the waves going through the top of the display and did not list the sea conditions as gale, strong gale or anything like that. The conditions were described as phenomenal.
We talked with Captain Bang on a later cruise, and he said that the conditions were the second worst he had experienced in over 40 years on all types of ships, and that he never left the bridge for three days.
Blame it on senility, but I really enjoyed the rough seas.