Ryan Carroll and Evan Keir are taking on the Southern Upland Way in aid of Nith Inshore Rescue.
They hope to raise £3000 to help pay for the equipment needed by the water based charity, which union representative Evan, from Annan, has newly joined.
Their chosen route starts on the west coast at Portpatrick on June 18 and finishes on the east coast at Cocksburnpath and they’ll be carrying 20kg rucksacks each and will celebrate Evan’s 28th birthday on the way.
Ryan, 25, said: “The hike is going to take 18 consecutive days, on some of Scotland’s most demanding terrain and we’ll be carrying all of the items required to stop and make camp every night.
The friends, who met in the Scouts when they were younger, are already in training for the expedition and meet up every fortnight for a three day hike.
Ryan, who is originally from Eaglesfield but now works away as a marine engineer, said: “We are regular hikers but this hike is by far the most ambitious hike we’ve taken on.
“We chose Nith Inshore as Evan is a new member of their crew and because of my background working offshore. It’s vital that they receive donations as it is their only source of income.”
The lads have set up a website to document their journey, hikefornith.com, and also have a crowdfunding page for donations, it can be found at www.justgiving.com/fundraising/hike-for-nith.
