AN Olympian and the Wales women’s lacrosse squad were among 650 swimmers taking the plunge in tribute to a 13-year-old schoolboy on Sunday.

The swimathon at Monmouth School for Girls’ pool in memory of teenager Tom Walker racked up an incredible 619 miles - more than double the target of swimming the full length of the River Wye - and is set to raise more than £14,000.

And the 12-hour Swim for Tom marathon saw the fundraisers swim the length of the rivers Severn, Usk, Monnow and Conwy for good measure in an amazing charity effort.

The swimmers, who included Welsh Olympic star Thomas Haffield, made a giant splash in aid of Cancer Research Wales, as part of a major initiative to raise £100,000 towards a dedicated fund in honour of Tom Walker, a pupil at Monmouth School for Boys who died of leukaemia last summer at the age of 13.

The inaugural event was an overwhelming success as adults and children of all abilities showed tremendous spirit to rack up a whopping 39,532 lengths.

The original target was to amass 17,200 lengths or 268 miles to match the distance of the River Wye and back again.

However, the army of swimmers eclipsed the initial target by lunchtime and then proceeded to swim the length of the rivers Severn, Usk, Monnow and Conwy.

The young children at Monmouth Schools Pre-Prep and Nursery held their own event, totalling an impressive 688 lengths towards the final total.

The swimathon was organised by Tom’s sister Holly who was 13 on Christmas Day, fellow Monmouth School for Girls pupil Katie Cameron, 18, and school director of sport Lou Scott.

Katie said: “Everyone did their little bit and it was an incredible day. We had over 600 swimmers and 70 volunteers which was more than we anticipated.

“It was a day we will never forget.”

Tom’s parents, Debbie and Tim Walker, said: “It was an astonishing and special day for us.

“It was fantastic to see so many people of all swimming abilities and ages do their best.

“So many volunteers gave up their time to help and donations have more than doubled our initial target, so thank you to everyone.”

Tom was a keen swimmer for Monmouth School for Boys and the town’s Monnow Swimming Club and was also learning to row on the River Wye with the school rowing club.

Last month, Debbie, Tim and daughters Holly and Emily, 11, christened a new rowing boat, called The Otter, in memory of Tom, named after his favourite mammal.

The eight-seat boat was bought with funds raised by pupils who rowed Loch Ness last September and with money from Tom’s estate, and will be used widely by the school’s rowers in training and in competitions, including on the London 2012 Olympic lake.

Tom’s dad Tim said: “All money raised will go to a dedicated fund named after Tom that will be used by Cancer Research Wales to fund research into leukaemia.”

A bucket collection at the swimathon, food and Cancer Research Wales merchandise sales, a raffle, “Name the Otter” competition and cash donations, plus the Monmouth Pre-Prep collection and a Christmas Jumper collection by NFU Mutual totalled £5,240 in notes alone, with coins still to count.

The Walker family estimate that with the JustGiving donations, the coins and the cheques, the total raised will exceed £14,000.

Online donations for Swim for Tom have yielded more than £6,400 and can still be made via www.justgiving.com/fundraising/swimfortom