Three decades ago, a reporter plunged into wonder and danger.

We fell for an hour, as the views from our observation ports slowly faded to pitch darkness. That made it all the more interesting when at the bottom of the Pacific Ocean in our three-person submarine, a mile and a half down, the power went out and the lights went out.

It was my first underwater dive, in 1993. We were about 250 miles off the Oregon coast exploring the geological features of the seafloor in Alvin, a famous vessel operated by the Woods Hole Oceanographic Institution in Massachusetts. Our expedition entered its third week. Alvin had fallen repeatedly. Now it was the expedition’s final dive after days of frustration caused by bad weather and struggling to find what the scientists had been hunting. And finally it was my turn.

As a journalist fascinated by the technological feats of a new generation of small submarines, diving in a submarine helped me understand a number of things: the scientific importance of such dives, why humans can often achieve more in the deep sea than robots and why people are eager to take part in such dangerous pursuits. My experience also highlights the risks faced by the passengers of the Titan submarine when they decided to dive at the Titanic’s resting place.

Our own target was a gnarled lava field from a recent volcanic eruption that icy seawater had turned into a frozen lake of erupting fury. The scientists on the expedition, led by John R. Delaney, a geologist from the University of Washington, expected to find the field dotted with hot plumes of mineral-rich water that produced towering chimneys of rock and fed strange life forms, including scrub. of tube worms. But until now they had given up due to bad weather and material problems.

“May the force be with you,” a dive leader aboard the submarine’s mothership said over the hydrophone as we began our descent. For me Dr. Delaney and our pilot, Robert J. Grieve, this dive was an opportunity to end the expedition on a positive note. Each of us looked out of our own observation port and had a responsibility to tell each other what we could see in the submarine darkness.

If Alvin’s passenger compartment was cramped, it was surprisingly comfortable; it was lined with plush cushions and felt a bit like a compact spaceship. Dials and switches were plentiful for backup systems. Everything spoke of careful planning. Outside my observation port, I saw an endless parade of rippling, bioluminescent organisms.

We reached the bottom at about 9:30 am, flying over endless fields of pillow-shaped lava. After an hour of fruitless searching, we came to our first major discovery: a Reebok shoe that had sunk into the abyss, a shocking observation considering the severity of our hunt.

Slowly our little sphere got colder. I put on a sweater.

When the lights went out, my experienced companions insisted that nothing was wrong. Our pilot soon got us moving again, on backup power.

Then, at 11:30 a.m., after what seemed like many hours of viewing endless mounds of lava, we encountered a giant chimney looming out of the darkness.

“It’s hot,” reported our pilot, Mr. Grieve. “There are tube worms everywhere.”

A riot of life flourished on the otherworldly monolith, which was three or four stories high: tube worms four to six inches long, mats of white bacteria, and iridescent, dark red palmworms about an inch long. There were also swarms of miniature lobsters and at least two types of small corals.

We examined five large chimneys in total. Some of the little ones were actively releasing hot water, but were lifeless and quickly crumbled when Alvin’s mechanical arm tried to grab them. The hottest vent water we measured was 543 degrees Fahrenheit, hot enough to cook pizza and melt many modern materials, including tin.

We had to stay very still as Mr. Grieve used the submarine’s robotic arm to take samples and take measurements. At one point I started doing breathing exercises to relax.

Suddenly, Mr. Grieve noticed that the temperature of the submarine’s skin began to rise. We accidentally positioned ourselves over a hot vent, which was potentially dangerous as the submarine’s plastic windows could melt.

We quickly started our ascent, exhausted and happy.

I couldn’t imagine a robot doing what Dr. Delaney and Mr. Grieve accomplished during our plunge into the sunless depths. The two specialists performed a complicated dance of deft maneuvers based on close observations they made of the alien world around us. They also made quick decisions in the moment, moving quickly away from a serious threat.

On my way up I watched the flashes of living light and wondered what else was out there.