I was on this ship earlier this year; it is the Norrona which runs around the North Atlantic, operated by the Smyril Line. It must have been pretty scary; the north Atlantic is rough on calm day even when the engines are running.
The worst accident I have had was on a Norwegian ferry, a hydraulic pipe broke when they went to open the doors. Thankfully it was before passengers went down to the vehicle deck so no one was hurt but everything was covered in oil. Luckily for me I had left my helmet the right way up otherwise it would have been full of oil. They had the bike steam clean for me.
I would rather ride a 1000 miles than take a ferry.
I did a google once on ferry accidents and there are plenty around the world. After the Herald of Free Enterprise went down the European rules became stricter for the operation and specification of ships. The old ships which were too expensive to upgrade got sold the developing world.