I just came across this clip from Werner Herzog's Encounters at the End of the World (2007). What you can hear in it is fascinating: the sound of seals in the Antarctic are like nothing you could have imagined.

Personally, I learnt two things: a) that seals under Antarctica's ice sound like alien spaceships or Pink Floyd (more or less the same) and b) that the McMurdo Station is manned by a nun and a monk. Both are fascinating facts. [Thanks Andrés!]