The Mysterious Phenomena Known as the “Icicles of Death”

June 17, 2016 | Joanne Kennell

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What’s cooler than being cool? Brinicle-cold!

Deep in the ocean, a very beautiful, but deadly phenomenon occurs. Icy underwater tentacles, also know as brine icicles, or “brinicles,” can grow towards the sea floor from the base of Arctic and Antarctic sea ice. Although these sea stalactites are hypnotic in nature, they are also treacherous, hence their nickname the “icicles of death.”

This discovery of brinicles was actually pretty recent — the 1960s. But based on what we have learned about them so far, scientists think life on Earth may have originated from these tentacles, and that they may even harbor conditions suitable for life to form on other planets and moons.

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To understand brinicles, you need to know what happens when seawater freezes. Ice is made predominantly of water molecules, so when sea ice is forming, impurities like salt are forced out, which is why sea ice isn’t as salty as ocean water. As the salty pools of water leak from the ice, the surrounding water becomes more saline, lowering its freezing temperature and increasing its density. This increased density causes the brine to sink.

This is where it gets really interesting. As this extra cold, briny water reaches warmer seawater below, the water around it flash freezes, creating a descending tube of ice known as a brinicle. Sometimes an underwater icicle reaches the seafloor, and when it does, a web of ice forms and spreads, entombing and freezing everything in its path — including any unlucky sea life, such as starfish and sea urchins.

“In areas that used to have the brinicles or underneath very active ones, small pools of brine form that we refer to as black pools of death,” Andrew Thurber, a professor at Oregon State University, told Wired. “They can be quite clear but have the skeletons of many marine animals that have haphazardly wandered into them.”

In 2011, using time-lapse cameras, BBC filmmakers recorded the phenomenon in Antarctica. The formation took 12 hours, and once the brinicle reached the ocean floor, it spread along for 6 meters (20 feet).

Thurber, who is also a diver, has actually seen a brinicle bloom first hand. “They look like upside-down cacti that are blown from glass, like something from Dr. Seuss's imagination. They’re incredibly delicate and can break with only the slightest touch.”

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