A film-maker has captured stunning close-up footage of a Weddell seal swimming under thick winter sea ice at Antarctica.
Anthony Powell, who has spent the last year on the frozen continent, had been filming in frigid Antarctic water, putting his GoPro through a hole smashed out of the ice for a water intake at Scott Base, New Zealand's research facility on Ross Island.
"What I've been doing over the winter is, once every couple of weeks, chucking a camera down the hole there and recording for around an hour to capture the changes throughout the year," he says.
"Now we've got these Weddell seals appearing in greater numbers around the base and this is one of them swimming by and there's some vocalisation, it's pretty amazing the noises they can make."
Weddell seals stay on the ice all year round, even in winter when the sea is completely frozen.
"Occasionally you'll hear them calling under the ice and you'll just hear the sound permeating up through the sea ice when you're walking around," Mr Powell says.
"When you get a swag of them going at once it can be incredible to hear the ranges, and frequencies and the sounds they can make."
Mr Powell is an award-winning documentarian who received critical acclaim for the feature film Antarctica: A Year on Ice in 2014.
He has spent the last year filming yet another piece, this one a TV series, and putting together some educational material for Antarctica New Zealand.
He is heading back to the mainland next month, and says he's looking forward to seeing "greenery".