Deep in the waters along a volcanic ridge at the bottom of the Atlantic Ocean, marine explorers using a remotely operated vehicle to survey largely uncharted areas found a pattern of holes in the sand.
During the dive, north of the Azores, near mainland Portugal, on July 23, they saw about a dozen holes that resembled a trail of lines on the ocean floor, at a depth of 1.6 miles.
Then about a week later on Thursday there were four more sightings on the Azores Plateau, which is an underwater terrain where three tectonic plates meet. Those holes were about a mile deep and about 300 miles from the site of the expedition’s initial discovery.
The question that scientists ask themselves and the public in publications about Twitter Y Facebooken: What is creating those marks on the ocean floor?
“The origin of the holes has scientists stumped,” said the Twitter post from the National Oceanic and Atmospheric Administration’s Ocean Exploration project. “The holes appear to be made by humans, but the small piles of sediment around them suggest they were excavated by… something.”
Nearly two decades ago, just about 27 miles away from the current expedition’s initial sighting location, scientists spotted similar holes during a survey, NOAA spokeswoman Emily Crum said.
But the passage of time hasn’t provided clear answers, said Michael Vecchione, a NOAA deep-sea biologist who was involved in that project and is also involved in part of this latest expedition.
“Something important is happening there and we don’t know what it is,” said Dr. Vecchione. “This highlights the fact that there are still mysteries out there.”
The holes are just one of the questions scientists are investigating on an ambitious ocean expedition as they explore the Mid-Atlantic Ridge, which is a section of a huge deep-sea mountain range and extends for more than 10,000 miles under the Atlantic Ocean.
NOAA experts are looking for answers during three expeditions they are calling Voyage to the Ridge 2022, which began in May and will conclude in September, on voyages that will take them from the waters off Newport, RI, to the Azores and back to Puerto Rico in the Caribbean.
The explorers want to know what lives along the continuous chain of underwater volcanoes and what happens when the geological processes that create the heat that sustains life stop.
They’re paying close attention to deep-sea coral and sponge communities, which are “some of the most valuable marine ecosystems on Earth,” said Derek Sowers, expedition coordinator aboard NOAA’s ship, the Okeanos Explorer.
Dr. Sowers said expeditions such as the Voyage of the Ridge projects were “instrumental” in establishing an understanding of the planet’s biodiversity and “the new compounds produced by all these life forms.”
And they want to know more about areas where magma warms seawater, with deep-sea life deriving energy from this source and chemicals, rather than the sun, like most life on Earth.
“This has expanded our understanding of the conditions under which life can occur on other planets,” said Dr. Sowers.
After the agency took to social media in an effort to engage the public, dozens of comments poured in, with some delving deeper into speculation. Are the holes man-made? Could they be a sign of aliens? Are these tracks left by a submarine? Could it be the breathing holes of a”deep sea creature that burrows under the sand?”
That last assumption wasn’t necessarily that far fetched, Dr. Vecchione said. in a article about the holes discovered in 2004, Mr. Vecchione and his co-author, Odd Aksel Bergstad, a former researcher at the Norwegian Marine Research Institute, proposed two main hypotheses as to why the holes exist. Both involved marine life, either walking or swimming on the sediment and drilling holes, or the reverse scenario, burrowing into the sediment and drilling holes.
The holes seen on Thursday appeared to have been pushed from below, Dr. Vecchione said.
The remotely operated vehicle’s suction device collected sediment samples to examine whether there was an organism inside the holes, Dr. Sowers said.
Dr Vecchione said that while he was pleased to find the holes in the ocean floor again, he was “a little disappointed” that scientists still lacked an explanation.
“It reinforces the idea that there is a mystery that we will one day solve,” he said. “But we haven’t figured it out yet.”
One last dive, which will be broadcast liveremains to be done in the second expedition of the series, NOAA said. The third expedition begins on August 7.