For the last 31 days, Guy O’Leary has been swimming a mile a day in the cold waters of Dublin Bay to raise money for cancer research. More than 100 people have joined him swimming either physically next to him or virtually in the sea or swimming pools in 15 cities around the world including New York, London, Vancouver, Barcelona and Dar es Salaam. This afternoon he will swim his final mile alone, starting in Scotsman’s Bay near the Boyd Memorial on the East pier of Dun Laoghaire before swimming around into the harbour to finish at the Royal Irish…