How is it different?
Ice and animals - mainly charismatic megafauna at that.
The southern ocean it is permanently cold, but it is a very rich and productive sea. Ice in the form of endless pack, towering bergs or just everyday bergs and bergy bits can turn up from no where - they are reminders of how restless and unpredictable the southern ocean is.
Seals and penguins - whales if you are lucky - turn up in mid ocean on their way to fishing grounds or back to land. It reminds you that you are in a large active ecosystem. Other oceans don't have such readily visible activity, especially a long way from land.
Would you say it's tied to the sea being powerful, or you felt you had to work with it's conditions or moods, or because it's not our native environment, or perhaps something else?
It's because that's the way it is. The sea does what it does and everything else fits in with it. The nice thing about the southern ocean though is that it has more variety in terms of ice, weather and wildlife than other oceans. I see the word "moods" as being unwarranted anthropomorphising, the sea responds to the physics of the weather and everything fits around it as nothing can alter it.