THREE of the world’s toughest open water swims were no match for an Oxford-based researcher who became just the seventh person to complete them all.

Dr Victoria Cox swam 46km around Manhattan island in New York on September 8, less than a month after completing a 34km swim across the English channel and two months since she crossed 33km from Catalina Island to mainland Los Angeles.

Amassing a total of 113km over 36 hours, she became the seventh person to complete what’s known as the ‘triple crown’ of open water swimming in one season.

The 27-year-old, who trained for the mammoth undertaking by swimming 50km a week in the Rosenblatt pool in Iffley Road and Queenford Lakes near Dorchester, said that completing the challenge was '80 per cent mental and 20 per cent physical’.

She said: “It is not like running a marathon where there are lots of people supporting you along the way.

“It's just you, the water and a small support team on a boat nearby.

"You have to keep putting one arm in front of the other and have courage and faith in the fact that you will be able to get there.

“When crossing the channel you can see France four or five hours before you arrive.

"It just never seems to get any closer.”

Dr Cox, originally from Australia, began open water swimming ‘by accident’ in 2011 when friends dared her to try the Rottnest Channel Swim that takes place every year near Perth, Western Australia.

It helped her prepare for the gruelling exercise 'triple crown', when she had to contend with container ships, cold waters and swimming at night when crossing the English Channel.

Thousands of jellyfish live in the waters between Britain and France and swimmers can be stung ‘up to a hundred’ times whilst attempting the crossing.

Condensed carbohydrates, described by Dr Cox as ‘not particularly inviting’, need to be taken on every half an hour to keep strength up, but the 10-to-15-seconds spent feeding is the only break allowed in the 12-hour swim, which is strictly governed by officials.

The researcher, who has a medical degree, is half way through a postgraduate degree in social policy at Oxford University and is now gearing up to swim to France again as part of a team of six competing against Cambridge University in the 2018 Varsity Channel Swim.

Dr Cox, who hopes to encourage more people to start open water swimming as part of her role as captain of the team, said:“It’s such an amazing community.

"Throwing yourself into cold water is not something that comes naturally to most people and it’s wonderful to have such welcoming and supportive people around you who are always happy to help.”