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.
The icy phenomenon is caused by cold, sinking brine, which is more dense than the rest of the sea water. It forms a brinicle as it contacts warmer water below the surface.
“When we were exploring around that island we came across an area where there had been three or four [brinicles] previously and there was one actually happening,” Mr Miller told BBC Nature.
The diving specialists noted the temperature and returned to the area as soon as the same conditions were repeated.