A veteran fundraiser aims to complete a gruelling hike up Snowdon in a diving suit weighing 130lb (59kg) on the last leg of his Three Peaks challenge.
Lloyd Scott, 58, who has already walked up the highest peaks in England and Scotland, hopes to finish by Monday.
“If I had recced the peaks before I would have said it’s not possible,” he said.
He has so far raised more than £46,000 for the Lord’s Taverners which supports disadvantaged and disabled children.
Mr Scott, from Theydon Bois, Essex, is no stranger to tough challenges, having taken part in numerous charity events over 30 years, including completing the 2002 London Marathon in the deep-sea diving suit.
The former professional goalkeeper and firefighter can only see a few feet in front of each step as his helmet prevents him from looking down, so he is guided by helpers.
Support team member Tom Warner paid tribute to his gritty determination since seeing him conquer Scafell Pike and Ben Nevis.
“He’s as a hard as nails mentally,” he said.
If all goes to plan, he hopes to start his final push to the summit of Wales’ highest peak on Monday morning as his pace means he has to camp overnight with each ascent taking place over two days.
He has been consuming in excess of 5,000 calories each day, using high-energy drinks and food, including pizza, to keep his energy levels topped up.
But he has already lost about 1st (6kg) since starting the challenge in Scotland last weekend.