Royal Marine Commandos armed with thermal imaging equipment patrolled the course of the Oxford and Cambridge Boat Race in a tightening of security following disruption last year.
Organisers were anxious to avoid a repeat of last year when the race was disrupted by a protester, Trenton Oldfield, who swam in front of the Oxford and Cambridge university crews and narrowly avoided being struck by an oar.
Up to ten rigid inflatable boats manned by Commandos patrolled along the four-and-a-quarter-mile course, as organisers warned potential 'copycat' protesters to stay away from the race.
Organisers warned against a repeat of anyone taking to the water for the 159th race and advised that as well as the course being monitored by Royal Marines police were also watching social media for any signs of a planned disruption of the event.
Boat Race executive director David Searle said before the race: "We are taking additional measures this year and have reviewed all of our actions last year in detail.
"The Boat Race course is four and a quarter miles long so we have eight and a half miles of riverbank to manage and monitor.
"What I would say to anybody thinking of disrupting the race is that it's unbelievably dangerous. You risk injuring yourself, the crews and the other people following the race.
"Nobody wants that to happen. This is just a sporting event."
Trenton Oldfield, 36, was released from prison in December having served seven weeks of a six-month sentence after being found guilty of causing a public nuisance.
He was contacted by the Metropolitan Police by letter and on Twitter to establish whether he was planning any action this year, saying they were "keen to facilitate any peaceful protest".
Earlier this week Oldfield told the Independent that he had no regrets about his protest, which he claimed was aimed at beginning a discussion over inequality and elitism in Britain, but that he would not be anywhere near the Thames today.
Oldfield told The Spectator he would "probably have a ramble across the Cotswolds instead".
In the end the race passed off without incident. Oxford University beat Cambridge by a length and a half to win.