Jackson has decided to walk 100 miles for his former friend and Surrey cricketer, who was tragically killed by a London Underground train in June.
"We were mates from day one," said Jackson. "Obviously it was a shock. I still struggle to believe it now.
"However, life goes on and I know he wouldn't want me to be moping around feeling sorry for myself, although I'm not sure he would have expected diving head first into the rainforest would be on the agenda."
Jackson first met Maynard when they were 12 years old at Millfield School in Bath.