A man from Cornwall paralysed during an RAF fun day could have avoided injury if a ban on diving into a shallow pool had been imposed, a judge has heard.
Robert Uren was trying to collect toys from a pool in a race when he dived in, slipped and fell at RAF High Wycombe.
Sir Geoffrey Nice QC said the 24-year-old ex-airman was "actively encouraged" to make a "head-first entry".
Mr Uren is claiming £6m in damages. The MoD and event organiser Corporate Leisure deny negligence and liability.
Mr Uren, from Camborne, was taking part in an "It's a Knock-Out"-style event at RAF High Wycombe, Buckinghamshire, in July 2005.
He was participating in a relay race in which service personnel had to run 45ft (14m) before retrieving the fruit-shaped toys from the bottom of an inflatable pool when he was injured.
He was taking evasive action to avoid participants already in the pool and slipped, striking his head on the bottom and fracturing his spine, resulting in his being paralysed from the waist down.
Sir Geoffrey Nice told Mr Justice Field that the "central issue" for the judge to resolve was whether Mr Uren was "encouraged and allowed to do something that was dangerous and should have been known to be dangerous".
Addressing claims that Mr Uren brought disaster on himself by diving into a pool he knew was too shallow, Sir Geoffrey said he had acted with the encouragement of the event's organisers, who "should have assessed the risks".
The court heard that Corporate Leisure (UK), of Calfridus Way, Bracknell, was expected to produce evidence that participants were expressly warned not to dive into the shallow water despite Mr Uren's insistence that he heard no such warning.
The case, being held at London's High Court, continues.