The unit runs off of a commercial camera battery.

Harbour porpoises and minke whales are often seen, too, so remember to charge the camera batteries the night before.

But they should really save their camera batteries for something really spectacular: the world's biggest sand island.

Operators will provide thermal clothing, but you should bring hats, scarves, gloves (plus several spare pairs) and extra camera batteries.

With solar panels, he kept his phone and camera batteries charged.