GALVESTON, Texas -- Princess Cruises is investigating how two passengers fell from a cruise ship into the Gulf of Mexico early Sunday.

Rescuers using high-powered spotlights searched for four hours before plucking the pair from the water. A spokeswoman says they sustained minor injuries.

A Coast Guard swimmer involved in the rescue says he's impressed the two survived. Micah Franklin tells NBC's "Today" show that waves were swelling up to six feet and the wind was gusting up to 30 miles per hour. He says the fall of 50 feet or more would have at least knocked the wind out of them, and then they had to survive four hours at sea.

The cruise line says the balcony from which they fell had a railing at least four feet high and meets all standard safety requirements.