Puffins seem most at home when they're at sea. Their final winter destination is in waters over epic “coral canyons” that go deeper than the Grand Canyon, and huge submerged mountain ranges that stretch for hundreds of miles along the ocean floor, according to the National Audubon Society's website. The zone is known for its rich biodiversity and offers an abundant food supply for puffins.

A researcher tags a puffin with a GPS tracking device.

GPS transmitters made it possible for researchers to track the puffins to their winter fishing grounds about 200 miles Southeast of Cape Cod.

A researcher shows the tracking devices used in the 2014-2015 study. Earlier studies failed because of faulty data or defective devices.

Atlantic puffins spend only about four months on land. These birds are from one of the colonies off Maine's coast: Seal Island National Wildlife Refuge and Matinicus Rock.

Stephen Kress/National Audubon Society

Stephen Cress, founder of the Puffin Project, has spent more than 40 summers studying puffins off the coast of Maine, but he never knew where the puffins went in the winter. Now, thanks to GPS tracking, he knows the answer.