A 36-year-old British man is to try to become the first person to swim the Thames from one end to the other. Lewis Pugh will set off from the river’s source close to the Welsh border next Monday 17 July, and hopes to complete the journey, stretching roughly 200miles to the North Sea, within 15 days. The Investec Thames Challenge has been set up to draw attention to a campaign by the WorldWide Wildlife Foundation against climate change. By swimming the Thames, Pugh hopes to highlight the need for us all to take action on climate change now.

The endurance swimmer has previously made waves by breaking long-distance swimming records in the icy waters of both the Arctic and Antarctic. In doing so, he became the first person to complete long-distance swims in all five of the world’s oceans.

The challenge facing Pugh is a tough one, but he’s used to dealing with adverse conditions. During the Arctic swim, Pugh covered more than 1km in icy 3°C water wearing nothing but a pair of Speedos, a cap and goggles, prompting the governor of Svalbard, Norway, to exclaim: “He is a polar bear!”