Royal Marines will be stationed in inflatable boats along the length of the Boat Race course on Sunday to ensure the event is not disrupted by another protester, organisers said.
Last year's race had to be halted when Trenton Oldfield swam into the path of the two crews and narrowly avoided being struck by an Oxford oar.
Boat Race executive director David Searle promised improved security along over eight miles of Thames riverbank and warned against anyone taking to the water.
"We are taking additional measures this year and have reviewed all of our actions last year in detail," Searle said.
"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.
"There will be an increased presence both on and off the water, including support from the Royal Marines, but as with any security plan I cannot disclose the exact details.
"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."
Oldfield, who claimed to be protesting against elitism, was released from prison in December having served seven weeks of a six-month sentence after being found guilty of causing a public nuisance.
The Metropolitan Police Service contacted Oldfield by letter and on Twitter to establish whether he was planning any action this year, saying they were "keen to facilitate any peaceful protest".
In a statement, the police stressed they were not offering to organise a protest but to afford him the opportunity to exercise his "lawful rights without causing disruption or danger to themselves or others".
However, Oldfield told The Spectator that he would be nowhere near the Tideway on Sunday.
"In spite of the Metropolitan Police's kind offer I'll probably have a ramble across the Cotswolds instead," he said.
Last year's race was eventually restarted after Oldfield was fished out of the water but his intervention was only the start of the drama.
Oxford, who had been narrowly ahead when the race was stopped, suffered a broken oar in a clash soon after the restart and ended up losing by more than four lengths.
Bowman Dr Alex Woods then passed out after the Dark Blue crew had crossed the finish line and he was taken to hospital by ambulance, where he spent the night before being discharged.