At a depth of 3,700 meters (12,000 feet), dozens of natural chimneys stick up from the seafloor emitting hot fluid at 290 degrees Celsius (554 degrees Fahrenheit). Over thousands of years, towers of lime have piled up. This is the hydrothermal vent field of the Pescadero Basin, about 150 kilometers east of La Paz in Mexico in the Gulf of California. A marvelous place!

US researchers at the Monterey Bay Aquarium Research Institute discovered the deep-sea vent field at Pescadero Basin in 2015. A few months ago, a research team went back on board the Schmidt Ocean Institute ship ‘Falkor’ to explore this special place. They mapped the seafloor, recorded high-resolution video and brought back rocks and animal samples.

Due to volcanic activity underground, hot water creeps out of the seafloor, containing chemicals such as hydrogen sulfide - a gas that smells like rotten eggs. It is extremely toxic to humans, but some bacteria can metabolize it and gain energy from it. Those bacteria thrive down here at Pescadero Basin and form these thick, fluffy looking bacterial mats.

The vents are buried in the sediment, so the hot liquid reacts with rocks before it escapes. Therefore, the liquid is clear (like you can see in this picture). At another type of vent called a 'black smoker', dark, metal-rich fluid leaves the chimneys instead. Pescadero harbors life quite different from that what was found at other vent fields explored previously.

The vents are densely covered with tubeworms (Oasisia alvinae). These sessile invertebrates live in chitin tubes just a bit wider than their body. Tubeworms like this one were discovered in the 1970s at a vent field near the Galapagos. The researchers were amazed by how many of these animals live at Pescadero. They are literally everywhere.

Oasisia tubeworms don’t have a mouth or a digestive system. Instead, the animals take up hydrogen sulfide and oxygen from the water with their orange-red plumes. They feed the nutrients into a bag filled with bacteria. The bacteria then generate energy for them. It works similar to the bacteria in our guts digesting food for us.

In Pescadero Basin, researchers found species they hadn’t seen anywhere else before. Like this iridescent blue scale worm, named Peinaleopolynoe orphanae. Across their back, they have thick discs that refract light - just like the wings of a butterfly. The researchers watched the creatures fighting with each other. They have big jaws which they can project during a fight.

This strange creature is called Xenoturbella profunda, but scientists often call it simply the “sock worm”. This turns out to be quite literal — they are just a bag with a mouth underneath. Scientists saw these strange animals gliding very slowly over the seafloor. They seem to feed on clams, as researchers found clam DNA inside their bodies. How they catch and eat their prey? Nobody knows.

Some animals — such as tubeworms, scale worms and Xenoturbella — live directly on the hydrothermal vents. Others, though, just float by, like fish or octopuses. Or this guy here, a siphonophore. It resembles a jellyfish, but it's not one. It’s more closely related to the venomous Portuguese man o' war.

Apart from animals and rocks, there is more to see in the Pescadero Basin. Underwater lakes like this one, for example. They develop when hot fluid gets trapped under rocks or within caves and cannot escape.

An underwater-robot pilot on the ship steers the remotely-operated vehicle from vent to vent. Via a tether, the robot sends back data and high-resolution video footage to the surface. The researchers can thus see in real-time what’s going on down there. An awesome experience, for sure.

The underwater robot has an arm with which it can pick up rocks and animals and bring them back to the surface. But most animals lose their colors and shape pretty soon when conserved in alcohol in the researchers’ lab. This for a example is a sea cucumber from Pescadero Basin, beautifully colored in life – not anymore.