The Antarctic predators are Leopard seals.Farther north you might have Frigate birds and other avian predators. The deep-diving penguins can see them on the surface as they return from dives. An object on the surface in clear water looks like it's floating in the sky so thats a possible answer.
Thanks RtS. "Drainpipe" trousers are(I guess) what we call "stovepipe" over here, so my question was valid after all.

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