THENEWYORKER,M AY18, 2020 39
a U shape, and he wouldn’t fall out.
“You get these nasty systems rolling
through, with just little gaps between
them,” McCallum told me. McCallum
has seen waves in the Southern Ocean
crest above ninety feet. He had carefully
mapped out a dive window, between
gales, and brought on board an ice pilot
and a doctor. “If something goes wrong,
there’s no port to go to, and there’s no
one to rescue you,” he said.
Albatross trailed the ship for the
first several days. Soon they disappeared
and the crew began seeing whales and
penguins. “Filled with trepidation, we
steamed into the teeth of the area where,
on the old maps, they used to write, ‘Here
Be Monsters,’” Vescovo told me.O
n the forecastle deck, in the con-
trol room, a cheerful, brown-haired
Texan named Cassie Bongiovanni sat
before four large monitors, which had
been bolted to the table. Bongiovanni,
who is twenty-seven years old, was finish-
ing a master’s degree in ocean mapping
at the University of New Hampshire
when Rob McCallum called and said
that he needed someone to run a mul-
tibeam sonar system for one and a halflaps around the world. She graduated at
sea while mapping Vescovo’s dive loca-
tion in the Puerto Rico Trench.
As the head sonar operator, Bongio-
vanni had to make perfect decisions
based on imperfect information. “The
sound is generated from the EM-124,
housed inside the giant gondola under
the ship,” she said. “As it goes down, the
width of each sound beam grows, so
that in the deepest trenches we’re only
able to pick up one point every seventy-
five metres or so.” In these trenches, it
takes at least seven seconds for sound
to reach the bottom, and another sevenThe Limiting Factor is the only vehicle “that can get to the bottom of any ocean, anytime, anywhere,” Rob McCallum said.