Video shows shows two divers from below descending into dark blue water under the sea ice. The divers are swimming with lit flashlights and are holding onto a line that provides a path back through the surface ice.
Voice: Sea ice is found near the north and south poles of the earth. In the summer it melts a little and in the winter it refreezes. Recently, scientists have noted that it is not refreezing as much. It is home to many plants and animals including the endangered polar bear. It is a good physical indicator of climate change and if it disappears completely, the animals and plants that live there may become extinct.