It’s an image those who have seen it will never forget: the moment a submarine’s windows reveal their first glimpse of the ocean floor.

Earth Sciences graduate student Sarah Moriarty got to experience the rare sight for herself this spring on a research cruise north of the Galapagos Islands.

A different perspective

Ms. Moriarty was invited aboard the R/V Atlantis, which also holds the human-occupied vehicle (HOV) Alvin.

The purpose of the five-week trip was to collect samples from active and dead hydrothermal vents located along a volcanic ridge at a depth of 2.5 kilometres to better understand how the microbial communities they contain change once a vent dies.

“She did really well out there and impressed a lot of people,” said Dr. John Jamieson, Ms. Moriarty’s supervisor, who joined her on the research cruise.

“They make you go inside Alvin, while it’s still on the ship, and you sit there for a little bit as they go over how everything works, the safety protocols and all of that. But part of it is they’re watching to see how you react. I’d say around 10 per cent of the people who get in there take one look and say, ‘Nope, can’t do it.’”

But the opportunity to do a dive in Alvin did not faze Ms. Moriarty.

“It’s a little bit claustrophobic, but surprisingly not as bad as I would have expected,” she said. “It’s amazing to be able to see everything and we were all leaning past each other to get different perspectives out the windows.”

Biological hotspot

Active vents are biological hotspots, attracting predators who feed off the animals who feed on the bacteria living in the vents.

While underwater in the Pacific, Ms. Moriarty got to view a diverse cross-section of ocean life, including crabs, mussels and octopuses.

Watch some footage taken by the HOV Alvin of alvinellid worms, which only live on active vents in the Pacific Ocean. This family of worms can live in temperatures of up to 55°C.

Alvin usually launches right after breakfast, around 8 a.m., and is back on deck by 5 p.m. The sub takes about 1.5 hours to get to the bottom of the ocean and another 1.5 hours to return to the surface.

“The weather was so nice we got an extra dive in during the trip, which is extremely rare,” said Ms. Moriarty. “There was even a night recovery of Alvin, which is something they hadn’t done in years.”

In the shade

The cruise was also joined for a few days by a BBC Blue Planet Live film crew. They travelled with the ship from San Francisco to the Davidson seamount, an underwater volcano off central California, to get footage of the largest octopus garden, or nursery, ever discovered.

“It was all very secret,” said Ms. Moriarty. “They wouldn’t let us tell anyone where we were going.”

Mapping and data management

During the remainder of the cruise, Dr. Jamieson collected rock samples so he could determine the age of dead chimneys. Ms. Moriarty was responsible for producing maps of each submersible dive and where samples were collected.

“Data management and mapping are vital, but a bit of a nightmare because everyone collects data in a different way, and what you think is important might not be to someone else,” said Dr. Jamieson. “But that’s what happens when you work with a big team. So, Sarah has to put all that together into a large coherent data set.”

Dr. Jamieson expects Ms. Moriarty will be kept busy post-cruise helping all the scientists involved with the publications that will come out of their respective trips.

And while the work didn’t relate directly to Ms. Moriarty’s thesis, it didn’t stop her from collecting samples for a number of new ideas, some of which do relate.

The team also left a number of experiments on the seafloor to continue collecting data. Discussions are already underway to return to the Galapagos to collect them next year.