It's almost six am and a north westerly is cutting its bitter way across the Bristol Channel. But Barry Gray is undaunted.
As befits a man who was part of a team that recreated Shackleton's epic 800 mile sea and mountain crossing from Elephant Island to South Georgia.
Even so the 115,000 feet of climb and 630 miles ahead of him will be no walk in the park.
A local runner started off with him as he made his way toward Porlock, Royal Marines are joining him too but he's invited anyone and everyone to run with him, to be part of the journey.
He's hoping to beat an 11 and a half day record for the path set by a North Devon man.
To put this in perspective, what he is attempting to do is cover almost two and a half marathons a day whilst climbing more than three times the height of Snowdon, and that's every day for ten days.
He's hoping to raise £10,000 for service charities, including one called The Baton. It's symbol is part of a stretcher from Afghanistan.
"I've lost lots of friends in the Royal Marines and I've got a lot of friends that need a lot of life long support, through care support for the rest of their lives. It's really important to them and their families. We're a small organisation, a small group of people who do a phenomenal amount to look after ourselves."