The submersible exploring the Titanic's wreckage went missing about 900 miles east of Cape Cod in Massachusetts Sunday morning activating a search-and-rescue mission led by the Coast Guard.

Journalist David Pogue says some of the five passengers on board the submersible were also part of the crew he was on last summer, including CEO of OceanGate Stockton Rush.

"I can picture all of it, I can picture what it is like to be on the ship, I can picture what it is like to get in the submersible, I can picture what it is like to sink below the waves," said Pogue. "I was scared, but you are with the guy who built the sub. He hasn't had an accident in three years, and he reassures you."

The minivan-sized capsule was less than two hours into its decent at the midpoint when the research vessel that guides it lost contact.

Pogue was on an expedition last year doing a story for CBS. He says passengers who pay hundreds of thousands of dollars are made aware of the risks — that mechanical issues happen. He says when he was there, the sub lost contact for several hours.

The journalist says there are two scenarios he can think of: his hope is that the capsule has made it to the surface and is awaiting rescue; and his fear, it is stuck on a net or something more catastrophic.

Pogue says it is possible the submersible lost power but says there are non-electrical ways to get the capsule back to the surface.