specialized foam as the sub for buoyancy, would serve as
navigation beacons for the craft on the seafloor, as well
as supplementary science platforms. Vescovo could use
Limiting Factor’s arm, for example, to grab rocks and bio-
logical samples, and deposit them in boxes on the landers.
Jamieson was arguably the busiest man on the boat. He
had to be up before dawn every day to prep the landers for
their trips to the bottom, and then on duty after dark when
they surfaced. In between, he worked with his team to
label and store samples, and study the latest sonar data.
In Pressure Drop’s control room, he pointed out
another area of interest on the map, this one to the east
of where Vescovo would dive. For eight years starting in
1973, the U.S. government designated a 193-square-mile
area of the trench (about the size of Tulsa, Oklahoma)
for dumping pharmaceutical waste. “The thinking was,
‘Deep water, who cares?’” he said.
Bureaucrats didn’t consider that these extreme deeps
had endemic fauna, or that such waste was toxic to
marine crustaceans. Even worse, Jamieson explained,
what falls into a trench has nowhere to go. Plates in sub-
duction zones shift slowly, on the order of 2 centimeters
a year. So, for eons, gunk just sits there, poisoning life.
Eventually, over the course of millions of years, Earth’s
mantle will absorb the icky stuff.
In other trenches, Jamieson has found microscopic
fragments of plastic in the bodies of animals, includ-
ing colorful threads clearly visible under a microscope.
In 2018, a study in the Mariana Trench found that con-
centrations of PCBs—flame-retardant chemicals that
entered commercial use in the 1930s and were banned
by the 1970s—were 50 times higher than you would find
in one of China’s most polluted rivers.
Here, however, Jamieson hoped to spy evidence of a
more positive development. Sea grasses, which gobble
carbon, fill these Caribbean waters. When hurricanes
tear up that flora, much of it then falls to the bottom,
and the decomposing organic matter feeds the tiny or-
ganisms that live there. “It’s a really nice story,” he said.
Carbon goes from the atmosphere and into a subduction
zone. “It ends up in the sediment, and gets pushed into
Earth’s mantle,” he said. “So the very deepest places in
the world are actually getting rid of carbon.”
Jamieson was optimistic about critter discoveries too.
For the past decade, he and his colleagues had been pur-
suing varieties of deep-sea snailfish—small, fragile pale
swimmers with tiny black eyes. They found the creatures
in a trench near Japan, near the bottom of Challenger
Deep, and off New Zealand. Earlier in 2018, he spied some
living in the Atacama Trench, off Chile. “They’re not the
same species,” he said, with some incredulity. “They’re
genetically not really related. But they’re at the same
depth, and look similar.” This suggests that these distinct1
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Dive 4: Pacific
56 FALL 2019 • POPSCI.COM
Vescovo dropped 10,928
meters during his first dive
to the world’s deepest spot,
the Mariana Trench, break-
ing the previous 1960 record
by at least 12 meters. He in-
sists he experienced current
near the area’s edge— as well
as spotted man-made trash
half-covered in silt. —MRx 13
Burj
Khalifas