Lewis was appointed as the UN Patron of the Oceans in 2013.

Ever since his appointment to this voluntary position, he has worked tirelessly to fulfil this brief.

As an endurance swimmer, he has a unique perspective on the oceans, one that makes him a compelling witness to the rapid changes taking place, especially in the Polar Regions and coral reefs; and he is uniquely placed to speak out for their protection.

In 2015, Lewis helped establish the largest Marine Protected Area in the world.

It was at a very challenging time geopolitically. The formal negotiations to protect this crucial ecosystem off Antarctica had dragged on for 17 years and had reached a stalemate. After a series of swims in the Ross Sea to focus the media spotlight on the issue, Lewis worked with key decision makers in Washington DC and Moscow, over a 2-year period, to keep the issue on their agenda and break the deadlock.

Today, the swim cap he wears for every swim sports the logo of the UN Environment Programme.