Hunting for morsels of plankton, a school of spadefish hovers near the surface off Japan's subtropical Bonin Islands. The turquoise color permeates the water late in the afternoon, as the red rays of the setting sun spread out and grow weak.
Sunlight streams between cracks in the ice. Thicker chunks glow emerald green, bejeweled by algae. The characters of this frosty realm begin to appear: a translucent, blue swimming snail, a pink fish with a tail like a geisha's fan, a bright orange lumpsucker that looks as if it leaped out of a Pokémon cartoon.
This is the underwater world that awaits photographer Brian Skerry, who is lumbering across the beach near a fishing town called Rausu, in Japan's northeastern corner. Wearing a hooded dry suit and carrying an air tank, hoses, regulator, and 32 pounds of weights, he pulls on his fins and slowly submerges his face to get used to the 29°F water. His lips go numb. And then, camera in hand, Skerry dives between the ice floes into the waters of the Sea of Okhotsk, bordering the Shiretoko Peninsula.
Most people think of Japan as a compact collection of large islands, but a map of the country shows otherwise. Japan stretches over 1,500 miles and includes more than 5,000 islands. As land mingles with sea over these vast distances, it embraces at least three distinct ecosystems. In the frigid north, sea-eagles, with their seven-foot wingspans, and king crabs frequent the ice-covered seas off the remote Shiretoko Peninsula. In the mild central waters of the Izu Peninsula and Toyama Bay, a few hours' drive from the skyscrapers of Tokyo, firefly squid swarm, and soft coral forests grow. In the balmy south, delicate butterflyfish and huge sand tiger sharks share coral reefs in the Bonin Islands, a collection of 30 or more islands about 500 miles south of Tokyo.