Cambridge University won a dramatic Boat Race against Oxford on Saturday, after a dramatic restart caused by a man swimming in the River Thames that raised questions about security for the London Olympics.
The drama continued after the restart of the race, which is now in its 158th year, when one of the Oxford oars snapped off and then an Oxford rower collapsed after crossing the finish line.
The two boats were side by side about eight minutes into the race in London when the man wearing a black wetsuit swam in front of the two boats, and was nearly hit by the oars of the Oxford crew.
Scotland Yard later said the swimmer had been arrested on suspicion of a public order offence and was being held in custody. It did not give any further details or identify him.
Spectator Mike Emerson said he had seen the man in his early 20s come through the trees on the south bank of the river and then get into the water long before the boats came past.
"He started swimming, he knew what he was doing," Emerson, who is 60 and from Cambridge, told AFP.
"He drifted down the river and then he waited near a pontoon until the boats came, and then he deliberately swam out toward the boats."
The man was pulled out by a lifeboat crew and appeared to have a broad smile on his face but his motives were not immediately clear.
Police boats and dinghies with flashing blue lights sped down the river to the scene and police helicopter circled the scene, an AFP reporter at the race said.
Both teams stopped rowing and umpire John Garrett halted the race after reserve umpire and former British Olympic rower Matthew Pinsent spotted something in the water.
"He (Pinsent) thought it was some debris and then we realised that it was actually a swimmer," Garrett said.
"We weren't sure what was going to happen, whether he (the swimmer) was going to get out of the way in time and then it was quite clear he was just waiting for the boats to come across him, so I had to stop the race and restart."
It restarted around half an hour later but seconds after that the crews clashed and one of the Oxford oars snapped off, leaving them trailing far behind by the end of the race.
There was further drama after the finish when Oxford crew member Alex Wood, 27, collapsed in the boat and had to receive medical attention.
Pinsent said he had seen Wood afterwards and he was sitting up and was conscious.
"I think it's hard to imagine a Boat Race that contained so much to talk about," Pinsent told the BBC.
The traditional post-race presentation ceremony was abandoned.
The race had been finely poised, with Oxford's "Dark Blues" having a lead of about a third of a length over their "Light Blue" rivals.
Umpire Garrett said the rules stated that crews "have to abide by their accidents.
"In the immediate run-up to the clash I was warning Oxford. Cambridge were in the right position so I was content to let the race continue and the result stand."
The last time the Boat Race was restarted was in 2001 when the crews clashed and one of them lost an oar.
Once just an event for undergraduates at England's two oldest universities, the Boat Race has become an increasingly international event, with a succession of top-class rowers from around the world eager to take part.
The disruption to Saturday's race raises questions about security ahead of an eventful summer in Britain.
While rowing events for the London Olympics this summer will be held at a closed course in Windsor, west of the capital, a flotilla for Queen Elizabeth II's Diamond Jubilee is set to proceed down the Thames in June.