The team of Peterborough firefighters from Red Watch took on the challenge to raise money for The Fire Fighters Charity.
Three Peaks involves climbing the three highest peaks of Scotland, England and Wales and includes 26 miles and a whopping 11,000ft of elevation.
Their first stop was Ben Nevis, in Scotland, on Monday, August 9.
On their first hike, they came across a walker who was injured and quickly turned their attention to helping her.
After contacting the local Lochaber mountain rescue team, they took turns carrying her down the mountain. When her condition deteriorated they performed immediate first aid until the mountain rescue team arrived.
After completing the hike to the summit slightly behind schedule, they headed to the Lake District to take on Scafell Pike.
Their final challenge was to conquer the summit of Mount Snowdon in Wales, which they completed in the early hours of Tuesday morning.
All three peaks were completed in under 30 hours by the team, who so far have raised £1,400.
Firefighter Callum Hodgkin said: “We completed all three summits together and made it back safely. There was a lot of teamwork and camaraderie to get through to the end.
“We've all picked up injuries, we've tackled a rescue, and we've overcome multiple challenges along the way – but we made it.
“We’re so grateful for the support we’ve received along the way and proud to have raised over £1,400 for The Fire Fighters Charity so far. Every penny will go a long way to help the charity continue to support the fire service community.”