DENVER -- A Denver man witnessed an incredible rescue of two people who fell off a cruise ship last week and caught the dramatic scenes on tape, which he shared exclusively with 7NEWS.

The two who fell overboard from the Grand Princess were Air Force cadet Ernesto Guzman and University of Colorado student Clarice Partee. They are expected to return to school Monday.

Shortly after midnight last Sunday, six hours after the cruise ship set sail from Galveston, Texas, the pair fell 50-80 feet off their cabin balcony into the Gulf of Mexico.

"He said they were both fooling around on the balcony and they decided they wanted to lean over and pretend they were in that movie 'The Titanic,'" said John Bornhofen, a cruise ship passenger.

The incident occurred in the middle of the night on March 25.

"It was completely pitch black and you couldn't see them, but you could hear them," said Bornhofen.

The couple's friends heard their screams as they fell over a ninth-story railing and the friends alerted the crew. The captain made an announcement over the loudspeaker at about 3 a.m., passengers said.

"We do know that two people went over the ship's side some time ago," the announcement said.

The captain retraced the ship's path, then turned off the engines and air conditioning and asked passengers to stay in their cabins.

Rescue boats were launched and all 2,783 passengers on the ship were told to be absolutely quiet so rescue crews can hear the two passengers screaming for help.

"They would yell, 'Help,' but that was it. You didn't know where they were, but you knew they were out there in the darkness," Bornhofen said.

The two were located by a U.S. Coast Guard helicopter, which used its spotlight to guide rescue craft from the cruise ship, the Coast Guard said.

After more than five hours, Partee was rescued. A short time later, a passenger heard Guzman screaming and crews finally spotted him in the water.

"And he kept on going under and then coming up, and then going under," Bornhofen said. "That was extremely hard to watch because you don't know if they were going to get to him in time."

But Guzman, 22, was rescued and jellyfish stings were his only injuries.

"Everybody is just so excited and screaming and yelling because now we know we have both of them and they are both alive," Bornhofen said.

How the two survived that long in the cold water amazes everyone.

"Treading water in a pool is one thing. Treading water in 5 foot swells, in 70-degree water, with jellyfish stinging you, that is a totally different situation," Bornhofen said. "Everybody I spoke to say they have no idea how they were able to stay afloat for that long."

The junior Air Force Academy cadet told officials with the academy that he credits his water survival training for keeping him alive.

Guzman remained aboard the ship and had fun for the rest of the cruise. According to passengers, he didn't seem fazed by what had taken place.

Partee, 20, got off the ship at the next port of call, in Costa Maya, Mexico.

Witnesses said she apparently broke a rib when she hit the water. She is a lifeguard from CU.