ALASKA

A storm sets in. When the ocean freezes over, polar bears head out on the pack ice to hunt.

A brown bear mother and her cubs come within feet of ecologist and bear biologist Chris Morgan. Watch video from Bears of the Last Frontier: City of Bears.

Admiralty Island hosts the largest concentration of brown bears in the world.

In this video, a bear is desperate to catch fish to feed her famished cub.

It's taken all spring and summer, but salmon finally return to Admiralty Island to spawn. Watch video.

Ecologist Chris Morgan and filmmaker Joe Pontecorvo decide to head out after an agitated polar bear begins to approach.

As loss of pack ice in Alaska's north increases, polar bears struggle to navigate an ocean of melting ice.

With help from its mother, a cub catches its first salmon at Brooks Range, high in the Alaskan Arctic.

Huge herds of caribou play an integral role in shaping Alaska's Arctic landscape.