Dr Mark Elvin swam 30.9K, the latest Swimathon Challenge, this September. The Swimathon 2021 officially took place on between Friday 10th and Sunday 12th September at over 300 venues across the UK. There are 5 individual challenges and 2 team challenges. The 30.9K is the pinnacle Swimathon challenge. It combines every single one of the regular, set individual and team distances, 9 swims in total.