HONG KONG — He and his shipmates stay up on the deck at night, sometimes watching rockets fly over their heads.

What was supposed to be an uneventful first voyage transporting oil across the Persian Gulf has turned into a nightmare for a 28-year-old sailor from India, who has spent the past month stuck as his ship sits idled by the Iran war.

“We don’t sleep at night. We stay up on deck because you never know what might happen next,” said the sailor, who asked not to be named for fear of reprisals from authorities and his employer.

The seafarer, who has been at sea since November, was speaking to NBC News from Iraqi waters minutes after an air attack Tuesday afternoon, which he says landed on Iran just a few miles away.

“The ship is still vibrating,” he said in an interview in Hindi.

He and the three other crew members on the small oil vessel are among 20,000 sailors stranded on hundreds of ships in the Persian Gulf, according to the U.N.’s maritime agency, after Iran effectively shut down the Strait of Hormuz in response to U.S.-Israeli strikes.

The blockade of the crucial shipping route, which has sent global energy prices soaring, has also trapped the largely invisible workforce that keeps the world’s maritime trade afloat, prolonging their time away from their families and putting their lives at risk. At least seven seafarers have been killed and several others have been severely injured in what the U.N. says were Iranian attacks on commercial vessels.

“The world has relied on these people to keep trade moving under impossible conditions,” said Angad Banga, chief executive of the Caravel Group, a Hong Kong-based shipping conglomerate that manages more than 600 ships, including some that are stuck in the Gulf.

It has already been a difficult few years for the world’s nearly 2 million seafarers, who mostly come from the Philippines, India and other Asian nations. During the Covid pandemic they were confined to their ships for long periods, unable to take breaks on shore because of border restrictions that many countries imposed.

Their work and mental health were further disrupted when Houthi rebels in Yemen began attacking ships in the Red Sea, with at least nine sailors killed and 11 others held captive for five months.

“The moment the crises fade from the headlines, the world forgets they exist, and that cycle has to break,” Banga added.

The International Maritime Organization, the U.N.’s maritime agency, has confirmed 18 incidents of damage to commercial vessels from March 1 to 19 in the Strait of Hormuz, the Persian Gulf and the Gulf of Oman. In one instance on March 11, there was an explosion on a Thai-flagged ship after it was hit by projectiles and 20 of its crew members had to be rescued, with three still missing on Friday as Iranian state media reported the ship had run aground off Iran’s Qeshm Island. Iran’s Revolutionary Guard Corps said the ship had ignored “warnings.”

Even if their vessels are not directly hit, the stranded seafarers can only watch in fear as Iran trades strikes with the United States and Israel.

In the incident Tuesday, the sailor said, he heard missile strikes for nearly half an hour and counted more than a dozen explosions.

“I was initially in the engine room so I didn’t know what was going on,” he said. “When I came up to the deck, I saw the rest of my crew watching the rockets fly by, which would be followed by explosions in the distance.”

“I could see when they were hitting the ground, see smoke rise and feel the impact through the ship,” he added.

The same day, Banga’s firm showed NBC News just how bad the situation has become.

Inside the Caravel Group’s headquarters in a Hong Kong office tower, in a room known as “the Bridge,” hundreds of white dots appeared across eight screens that formed a giant maritime world map, each representing a vessel under the group’s management.

The contrast is stark: While normally about 130 ships would pass through the Strait of Hormuz daily, some of them Caravel’s, virtually none are able to get through now. Several ships awaiting passage were visible on the screen.

As the stranded seafarers struggle to keep their spirits up, Banga said his firm has been conducting regular check-ins with crew members, who try to maintain somewhat of a routine that includes leisure activities and maintenance work on their ships.

“They exercise, they watch movies, some play basketball on the deck, sit there,” he said.

“When the routine breaks down is when people start to unravel,” he added. “The sun goes down, and that’s when the fear comes because most of the attacks happen in the dark.”

On Tuesday, the vessel tracking website MarineTraffic said in a post on X that only nine ships had passed through the strait since the day before, with apparent Iranian support.

One of them was a Chinese-owned vessel that successfully transited the waterway Monday.

A video shot by one of the sailors onboard the ship, shared on Chinese social media platform Douyin and geolocated by NBC News, showed the tanker passing through a narrow section of the strait off the coast of Bandar Abbas in southern Iran.

The sailor panned the camera around the ship, showing small speedboats in the distance that were escorting his ship and at least three other tankers in an apparent convoy.

“We can see some large tankers. Not sure why they decided to anchor here,” the sailor filming the video can be heard saying in Mandarin in another video, pointing to the Iranian coastline and some high-rise buildings visible in the distance.

“I can’t shoot any videos outside anymore. It’s dangerous. Let’s hide in the cabin quickly,” he says.

NBC News reached out to the vessel’s manager for comment.

Iran said this week that “non-hostile vessels” would be allowed safe passage through the Strait of Hormuz in coordination with Iranian authorities.

“As we repeatedly emphasized, the Strait of Hormuz remains open, and maritime traffic has not been suspended,” the Iranian Foreign Affairs Ministry wrote in a letter to the United Nations seen by NBC News. “Navigation continues, subject to compliance with the necessary measures referenced above and the realities arising from the ongoing conflict.”

The letter defines “non-hostile vessels” as those that “neither participate in nor support acts of aggression against Iran.” It did not say which countries qualify, though it said vessels “belonging to the aggressor parties,” namely the U.S. and Israel, did not.

The sailor stuck in Iraqi waters is hoping his ship will be able to leave soon.

“My family is panicking,” he said. “We’ve packed all our bags and are ready the moment someone calls us.”