Thanks gents for all the info on the stern viewing cab.

That cabin or enclosure on the stern deck is known as a "dog house." It's a shelter for the after controls station, in which the master of the vessel can steer, use the engines, etc. to take in a tow, or make up a tow astern.

There was a bigger cabin at this spot when the ship was named Sargasso Sea in 2007. Seems that is was removed in a 2012 picture and back now in a smaller version.

Only added recently it seems - perhaps a change in trade?

Even with the twin funnels, there was a pretty awful view aft from the wheelhouse, it seems.

Interesting cabin looking stern on afterdeck.