Additional safety measures will be introduced before the 2013 Oxford v Cambridge University Boat Race to avoid a repeat of last year's disruption.
In April, protester Trenton Oldfield swam into the path of the crews causing the
race to be halted,
before Cambridge won it after it had been restarted.
jailed for six months for causing a public nuisance.
Race director David Searle has appealed for no repeats in this year's event on 31 March, saying: "Please don't do it."
Boat Race factfile
The Oxford v Cambridge University Boat Race was first held in 1829 and has been held annually since 1856, apart from during World War I and World War II.
Oxford have won 76 of the 158 races, Cambridge have won 81 times, while the 1877 race was classed as a dead heat.
He added: "We've got eight-and-a-half miles of riverbank where somebody could go in so it is very, very difficult to stop someone if they want to do it."
Oldfield, who was released from prison in December, told BBC Radio 5 live he
did not regret the incident.
Without specifying what action was being taken, Searle insisted security would be increased for this year's race. "We are taking additional measures this year and we have looked at all of our actions last year," he said.
"We've reviewed them and thought about how we would react slightly differently, not much differently, if it happened this year. We had practised emergency stops and it worked. We got the race restarted eventually and it finished.
"What I would say to anybody thinking of doing that, is that it's unbelievably dangerous.
"You risk getting killed, which would be tragic for them and for the people involved. Nobody wants that to happen. This is just a sporting event."