This NJ man went diving in a submarine to see the Titanic. Here's what it was like.

When author and historian Charles Haas dove in a small submarine to see the wreckage of the Titanic 30 years ago, he knew the great risks he was taking traveling 2½ miles below the surface of the ocean to what he described as an alien world.

"It's not like diving off the Jersey Shore 50 or 100 feet," he said Monday evening. "It's a very, very dangerous endeavor. It's not an environment where human beings are welcomed."

Hass said he was heartbroken at news that a submarine carrying five people to the Titanic vanished deep in the Atlantic Ocean on Sunday night.

A rescue operation in the remote location — about 900 miles east of Cape Cod and around 13,000 feet deep — was underway to find the vessel, which had a 96-hour oxygen supply when it began its journey Sunday morning. OceanGate Expeditions, a Washington-based deep-sea exploration company, owns the submersible.

Haas, co-author of five books on the Titanic, was invited in 1993 to board the French research submersible Nautile for a voyage to the wreck. He was initially hesitant about the dive, knowing how deep it was, and spoke with his family about it.

"I was told there would be three tons of pressure per square inch at the depth we were going," said Haas, a retired history teacher. "But when I met the crew, I saw the meticulous care and preparation they took for each dive. They told me 'We want to come home to see our families, too.'"

'An underwater ghost town'

Hass was lying in a small titanium-cased cylinder with the crew for the duration of the trip — three hours to get to and from the wreckage and six hours near the ocean floor exploring it. He wore six layers of clothes, since the water temperature was near freezing at that depth. Water vapor from breathing condensed on the Nautile's ceiling and would drip on the three men.

But the uncomfortable conditions were worth it when he peered out of the tiny porthole at the ship he had spent so much time researching.

"I was beset by multiple emotions: joy of seeing an old friend, sad of the condition it was in and sad for those who lost their lives," said Haas, president of the Titanic International Society. "There was a tremendous sense of melancholy. It was like seeing an underwater ghost town."

"I'm very much heartbroken and distressed by this," he said. "I can only hope and pray that they are rescued."

This article contains material from the Associated Press.