A bizarre underwater "icicle of death" has been filmed by a BBC crew. With timelapse cameras, specialists recorded salt water being excluded from the sea ice and sinking. The temperature of this sinking brine, which was well below 0C, caused the water to freeze in an icy sheath around it. Where the so-called "brinicle" met the sea bed, a web of ice formed that froze everything it touched, including sea urchins and starfish. Read more
Embark on the trip of a lifetime, as the award-winning BBC team behind Planet Earth takes you on the ultimate polar expedition into a breathtaking landscape most humans will never experience. This landmark series brings to the screen the frozen wildernesses of the Arctic and the Antarctic in a completely new way. Read more