Mad Dog River Boarding operations manager Nicholas Kendrick said the way 21-year-old British tourist Emily Jordan was trapped meant the three guides couldn't rescue her, Radio New Zealand reported.
The guides did not carry ropes with them on the boat as they were a tangle hazard in the water, Mr Kendrick told the court.
After being trapped under water for about 20 minutes, a second boat from another company retrieved her body within minutes - using ropes.
He said the guides deliberately tried not to scare clients and kept things light-hearted.
All of the other members of the trip had managed to get around the rock that trapped Ms Jordan, and the guides had made a plan to navigate it, he said.
Ms Jordan's boyfriend, Jonny Armour, told the court via videolink from London that if he knew how physical the trip was going to be, they probably wouldn't have gone.
He said the guides were too light-hearted and even though they signed a waiver form against death or injury, the guides did not back it up during the briefing.
Mr Armour said he saw Ms Jordan's hand sticking up out of the water and as the minutes passed, he realised she must be dead. He was standing on the riverbank while rescuers recovered her corpse.
Mad Dog's director Brad McLeod and the company deny three charges each, laid by Maritime New Zealand under the Health and Safety in Employment Act.
Yesterday, prosecutors told Queenstown District Court Mr McLeod's boat was not carrying throw-bags or ropes the day Ms Jordan drowned.
The company was taking tourists on excursions when the river level was unusually low and had not briefed them on how to escape if trapped when riding on the modified wakeboard, the court was told.
