We put six questions to the British adventurer.
It's Autumn! Why are you in the sea?
I'm swimming in the cold windswept seas off Scotland en route to becoming the first person to swim the length of the UK from Land's End to John O'Groats. I'm three-quarters of the way and although the weather is getting colder the scenery is getting better.
So you're an experienced swimmer?
I haven't swum in 14 years. Last year I cycled 16,000 miles (26,000km) through six continents in 116 days completing the worlds first ever global bike race, despite being run-over early on and sustaining a fractured back.
What are your swim stats?
88 days so far, 650 miles (1,046) swum.
725,000 strokes in 12-16°C water.
11 jellyfish stings, four in the face.
Nine days swimming with dolphins, and 20 with seals.
Nine bad weather days, thrown up twice, and only had five showers.
What's your routine?
To get the most out of both tides, my first session usually starts at night, around 2-5am. I get up while the boat sails back to the GPS location from the previous session. Then I swim for four hours, feeding every 90 minutes. As the tide turns, we find an anchorage, then head back out for the second tide.
What about your gear?
I've used six Speedo Tri Super Elite wetsuits. I keep losing weight and needing smaller sizes. I wear gloves, booties, and three thermal tops under the suit. The layers aren't ideal, but at 62kg, I have almost no body fat and need the insulation. I use Speedo Aquapulse goggles, which are brilliant, and I vaseline my face against jellyfish.
Is there land ahoy?
I've got 200 miles (322km) to go. You can track my progress at swimmingbritain.co.uk