Iceberg Penguins

Photograph by Ralph Lee Hopkins

A group of chinstrap penguins lines the edge of an iceberg adrift in Antarctic waters. Chinstraps are among the most abundant penguins, and some colonies live on floating icebergs.

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Barracuda School

Barracuda School

Photograph by Tim Laman

A thick, swirling school of blackfin barracuda plies the blue waters off Sipadan Island, Malaysia. The fish are formidable predators, but they sometimes gather in groups for protection against sharks higher up on the food chain.

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Whale Shark

Whale Shark

Photograph by Brian Skerry

The sweeping color of sea and sky, blue is a common thread in nature, seen in the cerulean of a whale shark (pictured here), the indigo of a stormy night, and the cobalt of a peacock's feathers. Over the centuries, the hue has come to represent calm, cold, mysticism, and sadness.

http://photography.nationalgeographic.com/photography/photos/life-color-blue/

Neumeyer Channel

Neumeyer Channel

Photograph by Gordon Wiltsie

Icebergs drift across Antarctica's Neumeyer Channel. The Larsen Ice Shelf Expedition team predicts melting Antarctic shelves and bergs will raise sea levels around the world, flooding hundreds of thousands of square miles and displacing tens of millions of people. The team will collect evidence from their expedition to better understand how global warming is changing the continent and how we can prepare ourselves for its effects.

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Leopard Seal

Leopard Seal

Photograph by Paul Nicklen

A leopard seal plunges through Antarctic waters. Swift and stealthy, adult leopard seals tend to be solitary creatures, hunting alone at the fringes of pack ice. Finding a mate can be challenging given their isolation, but seals attract one another by singing—females to announce their readiness to a mate, males to serenade potential mates.

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Penguin and Chick

Penguin and Chick

Photograph by Maria Stenzel

An Antarctic gentoo chick stays near its parent for warmth. Gentoos are the fastest underwater swimming birds and can reach speeds of 22 miles an hour (36 kilometers an hour). Scientists worry that warming temperatures will encroach on penguin habitats, threatening their populations across Antarctica.

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Large Iceberg

Large Iceberg

Photograph by Bill Curtsinger

Global warming is forcing ice shelves to calve, producing icebergs like this monolith jutting into the waters of the Antarctic Peninsula. National Geographic's Larsen Ice Shelf Expedition team will examine calving shelves and the bergs they spawn, determining how shelves fragment and how diminishing ice mass affects the world's oceans and climate.

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