
Temperatures in the study were collected by narwhals, medium-sized toothed Arctic whales, during NOAA-sponsored missions in 2006 and 2007. The animals were tagged with sensors that recorded ocean depths and temperatures during feeding dives from the surface pack ice to the seafloor, going as deep as 1,773 meters, or more than a mile.
To read the full, original article click on this link: NOAA: Tagged narwhals track warming near Greenland | Science Blog