Skip to content

Volcanos, vents, and creatures of the deep, oh my (Part 1)

In 2015, Jason explored the inside of the Havre volcano on the seafloor near New Zealand. (Photo courtesy of Dan Fornari and S. Adam Soule, WHOI, and Rebecca Carey, Univ. of Tasmania/NSF/WHOI-MISO)

The ROV Jason Teams's most memorable dives


The Jason Team knows regions of the ocean floor like other people might know paths in their favorite mountain ranges. They've spent hundreds of hours in the ROV's control van where a bank of screens displays the deep sea from all angles. They've driven the vehicle over live volcanos, navigated to new hydrothermal vent fields, and encountered animals of all sizes. We've seen our share of breathtaking underwater landscapes during the PROTATAX23 dives, and we've heard adventure stories from other Jason expeditions. Here is a selection.

Fire underwater

The first time anyone captured video of an explosive volcanic eruption on the seafloor, WHOI Scientist Julie Huber and Jason Team members Tito Collasius and Akel Kevis-Sterling were watching it happen in real-time from the Jason control van

It was 2009. The science team was using Jason to explore the West Mata Volcano near Samoa because there had been a recent eruption detected in the water column. They were looking for seafloor activity, but with no disturbance on the ocean surface and no discoloration of the water, they weren't prepared for what they found when Jason dove. 

"I was in the van when we made our first approach," Tito said. "And we could see hydrogen explosions happening thousands of meters deep. They looked like balls of flame combusting underwater."

The lava flow was so fresh they could see features forming on the seafloor they recognized from cooled basalt seen on other dives. "We could see the pillow lava forming," said Kevis-Sterling. "It was still red and glowing."

The science team began to improvise ways to collect the fresh lava, recalls Huber. Dating cooled lava is notoriously difficult, and having a sample with a known origin date would be invaluable. "We tried a ladle, a coffee can, and finally settled on spinning one of Jason's T-handles in the flow."

The same year, on another expedition, Jason's cameras captured an erupting undersea volcano near the Island of Guam, NW Rota-1. Kevis-Sterling piloted the vehicle around the eruption.

"It was very active and gaseous, with lava shooting out," he said. "It is shallow there and was hard to navigate the ROV and the ship. At one point Jason was working near the volcano and it started going bonkers and spewed ash all over it."

When the ash settles

Erupting volcanos are hard to top, but Jason has also explored sites after an eruption and found once-familiar landscapes shockingly altered. A science team that returned to previously explored vents in Lau Basin in 2022 hoping to study deep-sea snails found some of their sampling sites buried deep in volcanic ash from the recent nearby eruption of Hunga Tonga-Hunga Haʻapai

"We were expecting diffuse flows, microbial mats, and snails, and instead it was smooth like the surface of the moon," said a member of the Jason team. "We brought a meter-long measuring stick down and couldn't find the bottom." Eventually they did find unaffected areas, but only after navigating down slopes of fine, diffuse ash. 

After the last eruption here at Axial Seamount in 2015, the science team returned to a familiar location in the caldera and asked Kevis-Sterling to check the coordinates again. "It was so unrecognizable that they thought we were in the wrong place," he said. "Everything we'd seen before was paved with lava."

Into the woods

The discovery of hydrothermal vents was one of the most surprising of the past century, revealing volcanically powered, deep-sea plumbing systems that enable vibrant islands of life that exist without sunlight. In its current second-generation configuration, Jason has often been the first vehicle to explore these sites as they are being discovered, offering video and sampling capabilities as scientists pioneer this field of study.

Even after diving on hundreds of vent sites, it never gets old for members of the Jason Team. 

One system that made an impression on Tito is at Lau Basin. Here, some of the vent's sulfide towers reach 30 meters (100 feet) tall. 

"It's like being in a redwood forest," he said. "You're working at the base of one of these towers, and the visibility in the ocean is only about 20 meters (65 feet) at best, but all around you can see the bases of other towers. It's like being in a forest only with hot smoke pouring out at the top." 

Huber was part of a WHOI team that first explored vents at the Mid-Cayman Rise in the Caribbean Sea in 2012. The rise is home to two very different vent fields, a deep one at a depth of 4950 meters (16,240 feet), and a shallow one at 3,000 meters (9,842 feet). 

he slender snorkel of an Isobaric Gas-Tight sampler (IGT) draws a sample of hydrothermal fluids spewing out of a hydrothermal vent chimney on the Cayman Rise as the mechanical arm of remotely operated vehicle Jason holds it steady. (Photo courtesy of Chris German, WHOI/NSF, NASA/ROV Jason 2012, © Woods Hole Oceanographic Institution)

"And the deep site has these very tall skinny chimneys, with 398°C (750°F) fluid gushing out the top of them," Huber said. "I remember there were five of them in a row-very well organized for random geology. They are really breathtaking."

And then, just 30 kilometers (18 miles) away, the shallow site offers a very different manifestation of hydrothermal activity at a place called the Von Damm vent field.

"There's no black smoke, all the fluids are clear, and at its summit there is a giant gaping hole so big you could fit Jason inside of it," Huber said. "You wouldn't do that of course, because the fluid coming out is about 220°C (430°F) and it is completely surrounded by shrimp. You approach it with the ROV and you feel like you're just peering over the edge."

Check back tomorrow, when we'll focus on some of the spectacular creatures Jason has encountered over the years.

- Hannah Piecuch

This NDSF blog series will follow the PROTATAX23 expedition to Axial Seamount, covering the science and scientists at sea, and the ROV Jason operations that make it possible. PROTATAX23 is funded by the National Science Foundation (NSF OCE Award #1947776).