A climbing instructor used to drive a teenage boy to a pub and buy him alcohol before assaulting him later at night, a court has heard.
Robert Pugh, now 75, is accused of eight charges of indecent assault, including some during camping trips.
He worked at the Storey Arms centre in the Brecon Beacons in the 1980s and 1990s, when the allegations date from.
Mr Pugh, of Cardiff, denies the charges at Cardiff Crown Court.
An alleged victim, who cannot be named, told the court the assaults against him took place in the early 1990s.
He had gone to the outdoor pursuits centre, run by Cardiff council, as a teenager and was invited back on a number of occasions as a trainee instructor.
- Climbing instructor 'groped boys on trips'
"In the evening, Mr Pugh would drive us to the pub. I can't recall paying for drinks. Mr Pugh would drink a similar amount and would drive us back to Storey Arms," he said.
"I remember sleeping in one of the beds, and that he tried to molest me. He rubbed around my crotch area, and I'd pretend to go to sleep."
During a camping trip, he said he was assaulted by Mr Pugh in a tent.
"He would try and touch me in the crotch area. I tried to leave the tent as soon as possible so he couldn't grope me."
Under cross-examination, he denied suggestions from Hilary Roberts, defending, he had created a "fictional pack of lies".
The court heard from another man on Monday who said he was assaulted during a camping trip in in the 1980s.
He told the court that during the night: "Bob basically got on top of me tried to rape me. He stuffed his hands down my sleeping bag."
He said Mr Pugh tried to reach his genitals, before being fought off.
The trial continues.