Deepest Dive Ever Under Antarctica Reveals a Shockingly Vibrant World.

Special report offers a rare look at life beneath the frozen continent—where penguins, seals, and exotic creatures thrive.Tendrils of ice-covered brine, or brinicles, leak from sea ice near East Antarctica’s Dumont d’Urville Station. Ephemeral and seldom seen, they form when trapped, supercooled brine escapes from the ice and freezes less salty seawate

Emperor penguins head for the open ocean in search of food. The brownish patches above them are microalgae that cling to the sea ice and start to photosynthesize in spring. The photographer’s day camp was on one of these floes. Aptenodytes Forsteri (penguins).

Tethered to the seafloor more than 200 feet down, siphoning in water to collect food, orange sea squirts “look very simple, like sponges,” says Chevaldonné. “Yet they’re quite evolved”—they’re invertebrates, but the larvae have spinal cords. Synoicum Adareanum.

A hundred feet below the ice, a feather star waves its frondlike arms, groping for food particles. It’s an animal, not a plant—a cousin of sea stars—and it can swim. Photographer Laurent Ballesta dived as deep as 230 feet to get these shots. Promachocrinus Kerguelensi.

A Weddell seal accompanies her pup on a swim beneath the ice. When the juvenile is full-grown, it will be its mom’s size: about 10 feet long and weighing half a ton. These placid seals stay close to the coast, breathing air through holes in the ice. Leptonychotes Weddellii.

An octopus jets above a seabed packed with life. Antarctica has at least 16 species of octopuses. All have a specialized pigment in their blood called hemocyanin, which turns the blood blue and helps them survive subfreezing temperatures. Pareledone sp.

A diver watches an emperor penguin as it swims nearby. The brown patches above are microalgae, which cling to sea ice and photosynthesize in the spring.

PHOTOGRAPH BY LAURENT BALLESTA.