John Ralph of Ascent Fitness created the Launceston Urban Fringe Trail, a 102-kilometre walking trail around the outer fringe of the city.

The Great Lonnie Stomp aims to bring more attention to the trails while raising funds for a great cause.

Participants are challenged to complete as much of the LUFT as possible within 49 hours, which started from 11.59pm on Friday.

"For this challenge some people will be walking through the night, so they will get a real sense for several hours of what it's like to have impaired vision," Mr Ralph said.

IN OTHER NEWS:

"We've been trying to keep it as flexible as possible, so people can start at any point and start and stop whenever they like."

Mr Ralph said participants' donations to Guide Dogs Tasmania would depend on how much of the trail was completed.

"After the event is over, they report in and say how far they went, and that calculates out of their entrance fee," he said.

Entrants are given comprehensive notes on the trail and an interactive map to use. 

Signs for the LUFT are also attached to signposts so that anyone can follow the trail, which runs through Launceston, West Tamar, and the Meander Valley.