Ocean

This stagnant brine pool at the bottom of the Gulf of Mexico is so toxic it kills and embalms any crabs and amphipods that are unlucky enough to stumble into it.

This 2018 astronaut photo shows the rust-colored waters of Madagascar's Betsiboka River winding through a complex series of mangrove islands. Both the river and islands have been altered in recent years by destructive human practices.

In 2018, satellite images captured a stunning spiral of cyanobacteria blooming in the Baltic Sea. The swirling mass of microbes helped to create a massive "dead zone" the size of West Virginia that starved the surrounding water of oxygen.

Alaska's melting permafrost is dumping toxic metals into the state's rivers, turning them bright orange and making the water highly acidic. The contaminated rivers are so vibrant they can be seen from space, and the problem is likely to get much worse in the future.

Atlantic currents slowed dramatically during the Younger Dryas period. By reconstructing those ancient ocean conditions, scientists think they can forecast changes over the next century.

A modeling study suggests a slumbering subduction zone below the Gibraltar Strait is active and could break into the Atlantic Ocean in 20 million years' time, giving birth to an Atlantic "Ring of Fire."

A new geological study suggests that Mars' gravitational field pulls the Earth closer to the sun over cycles lasting millions of years, warming our climate.

Permafrost thaw could result in new rivers forming across the Arctic, potentially unleashing 35 million car journeys' worth of carbon every year.

A vital Atlantic current that includes the Gulf Stream and keeps our climate in check may be giving off a warning sign of collapse.

Researchers have discovered a 33,000-foot-wide (10 kilometers) underwater canyon that was carved out of the Mediterranean seabed shortly before the sea dried up around 6 million years ago.