Crossing the Mid-Atlantic Ridge (MAR) feels a bit like flying over the Himalaya when they’re shrouded in clouds. In both cases, a dramatic landscape lies hidden from view. And yet, as we sail over this submerged mountain range, there will be a shipboard celebration. While others raise a glass, I’ll be thinking about the wonders that lie far below.
The MAR is a 16,000-kilometer mountain range that runs down the center of the Atlantic Ocean, from the Arctic to the Southern Ocean near Antarctica. It’s a place where tectonic plates are pulling apart—northern from southern, eastern from western—allowing magma to rise up from the mantle. This process, known as seafloor spreading, was explained by our onboard geologist Sam during his talk.
This isn’t my first encounter with the MAR. When I visited Iceland, I stood at a spot where the plates meet on land. Like many visitors, I placed one foot in Europe and the other in North America. No, I didn’t feel the spreading—it’s only a couple of centimeters per year—but the idea of straddling two continents is irresistible.
What I would really love is to ride in a submersible and see the dramatic valley and cliffs that form the ridge underwater. But what fascinates me most are the black smokers—deep-sea hydrothermal vents that give rise to unusual forms of life. The fluid from these vents can reach 350°C—far hotter than boiling water—but remains liquid because of the immense pressure at the seafloor. Near Tristan da Cunha, these black smokers lie about 3,000 meters below sea level, where the pressure is roughly 300 times that at the surface. No sunlight reaches that depth.
So what lives in such an extreme environment? Numerous scientific expeditions have ventured to the deep to find out. One of the most famous submersibles is Alvin. With over 50 years of missions and dives as deep as 4,500 meters, Alvin has given its three passengers—two scientists and a pilot—a rare glimpse into this harsh, hidden world. It helped discover hydrothermal vents in 1977, uniting geology and biology in a groundbreaking way.
The section of the MAR near Tristan da Cunha is so remote that it hasn’t been explored as thoroughly as areas near the Azores or other more accessible regions. But studies at those other sites have revealed an astonishing array of life: giant tube worms, clams, blind shrimp, and countless microbes that thrive in the vent environment. One of the most intriguing is a blind shrimp—Eurindicus bhugarbha.
These shrimp lack eyes as we know them, but they do have an organ sensitive to infrared light that can detect the faint glow of a black smoker. Inside their gill chambers, they host bacteria that digest sulfur compounds from the vent water. The shrimp farm these bacteria and, in turn, eat them. It’s a form of trophic symbiosis—a special kind of relationship where the host must encourage its food source to grow without consuming it into extinction.
And the shrimp are not alone.
Many other unusual creatures may be lurking beneath our ship as we cross the ridge:
• Dumbo octopus (Grimpoteuthis) – Adorably named for its ear-like fins, which flap like wings as it glides through the deep.
• Pompeii worm (Alvinella pompejana) – One of the most heat-tolerant animals on Earth, living in tubes clinging to black smoker chimneys.
• Deep-sea lizardfish (Bathysaurus ferox) – A fierce, big-eyed ambush predator with needle-like teeth and a fearsome bite.
• Vampire squid (Vampyroteuthis infernalis) – More mysterious than menacing; it can invert itself when threatened and emits glowing blue bioluminescent mucus rather than ink.
• Eelpout (Pachycara species) – Soft-bodied and ribbon-like, slithering through vent fields like a deep-sea serpent.
Crossing the MAR may look like just another day at sea, but beneath us lies a hidden world—fiery, pressurized, and brimming with life that thrives without sunlight. A party on the surface is fun, but I’m raising a quiet toast to the alien world below.
Comments