Named for the undulating waves of its broad, fleshy appendages—called parapodia—lettuce sea slugs appear in a range of colors ...

The wooden fishing boat chugs across Comau Fjord, a finger of dark water wedged between the snowy peaks of Chilean Patagonia. A Chilean flag flaps in the wind above a hand-painted black cormorant on ...

Each killer whale has a distinct pattern of pigmentation behind its dorsal fin. How do these patterns vary around the world?

Removing dams from the Klamath River in Northern California seems like a clear win for fish and rivers. Why do some locals hate it?

Removing dams from the Klamath River in Northern California seems like a clear win for fish and rivers. Why do some locals hate it?

Decades after they were hunted to local extinction, fin whales are recovering in the Kitimat fjord system—only to be threatened by a booming LNG industry.

A unique fjord in Chilean Patagonia gives scientists a chance to unlock the reproductive secrets of cold-water corals that typically live thousands of meters below the ocean’s surface.

Each summer, thousands of bluebottles (also known as Portuguese man-of-wars) wash up along the shores of Sydney, Australia. These remarkable relatives of jellyfish are actually colonial organisms: ...

One Great Shot: Are You Ready for This, Jelly? During a nighttime dive, a veteran underwater photographer captured a tiny fish’s cunning effort to find a safe spot in a dark sea.