The First Boat to the Bottom Read the Wrong Number

The gauge said 37,800 feet. It was wrong by about 2,000 feet, which is around 600 meters, and nobody knew it yet.

Two men were sitting inside a steel ball hanging under a tall tank of gasoline. Don Walsh was a US Navy officer and Jacques Piccard was a Swiss engineer. The boat was called Trieste. It had been built in Italy and was named after the Italian city. The tank full of gasoline was how it stayed afloat, because gasoline is lighter than water. Iron pellets pulled it down. On January 23, 1960, they were headed for the Challenger Deep, in the Mariana Trench in the Pacific Ocean. It's the deepest spot anyone has found in the sea.

The trip took almost five hours, and it got dark, then darker. Partway down, a loud crack shook the boat. One of the outer windows had split. They kept going.

At the bottom they stayed about twenty minutes. The mud they had stirred up clouded the view, so they left. Going up took a little over three hours.

Later checks put the true bottom closer to 10,900 meters, or about 35,800 feet. Even now, people give slightly different numbers, somewhere between 10,900 and 10,935 meters, depending on how and when it was measured. The figure of 10,994 meters that you'll see all over the internet comes from an older survey.

To get a feel for it, drop Mount Everest in. The top would still sit more than two kilometers under the surface.

Down there, the water presses on everything with more than a thousand times the pressure we feel in the air. A small car would be sitting on every patch of you the size of a thumbnail. That's why the Trieste needed a ball with walls thick enough to take it.

It isn't empty, though. Small shrimp-like animals called amphipods swarm any food that drifts to the bottom, and they live their whole lives there.

After 1960, nobody went back for 52 years. In 2012 the film director James Cameron dove to the bottom alone, and he described what he found as a flat, soft plain with almost nothing on it. In 2019 the explorer Victor Vescovo went too. He had already climbed Mount Everest, which made him the first person to reach both the highest and the lowest place on Earth. A few others have followed. In 2020 Kelly Walsh, Don Walsh's son, reached the bottom and stayed about four hours. His father got twenty minutes.

The place is named after British survey ships called HMS Challenger. Don Walsh was 28 years old on the day of that first dive. He died in 2023, at 92.