Ret. Navy Capt. David Marquet, a former submarine captain, described Wednesday what he imagines the five passengers are experiencing in the Titan submersible.
Marquet said he imagines the passengers are thirsty and hungry, but that it "is probably not going to kill them." If alive, he said they are likely to be very uncomfortable.
"They're freezing cold. The water entirely surrounding the ship is at freezing or slightly below. When they exhale, their breath condenses. There's frost on the inside of the parts of the submarine. They're all huddled together trying to conserve their body heat. They're running low on oxygen and they're exhaling carbon dioxide."
He told CNN's Jake Tapper the submersible has a "limited ability" to absorb the exhaled carbon dioxide, which at high levels could trigger headaches, confusion and nausea.
"The oxygen and the carbon dioxide and the freezing are what they got to hold onto as long as possible to give the rescuers the time they need," Marquet added.