Rangers recovered the body of Mary Simmons, 59, on Friday. The search is continuing for the remains of her husband, Donald Simmons, 64.
A thick sheet of rock broke from an alcove and capsized the couple's near Lake Canyon, about five miles downriver from Halls Crossing and Bullfrog.
The 250-square-foot rock slab apparently fractured from the wall of a 20-by-20-foot sandstone alcove where the pontoon boat was and crushed its bow.
Other boaters, who found the capsized vessel, told authorities they had passed the boat and waved to two people onboard about 20 minutes before it tipped over. The boaters contacted authorities at about 3:15 p.m. Friday to report the accident.
A diving team is searching for the missing man, but Karraker said underwater trees were impeding the search. The water near the search site is about 150 feet deep. An underwater robot was also being used.
Though the search for the missing man has been ongoing for four days, authorities don't have a set time when they will call off the recovery mission.
"We don't like leaving people down there," Marianne Karraker, spokeswoman for Glen Canyon National Recreation Area, said Monday.
