Lee Mack and Steve Coogan turned up in Windermere to show their support for Saturday's demonstration.
The march through the Cumbrian town was aimed at raising awareness of sewage pollution in England's largest lake, particularly with just a week to go before the general election.
This comes just over a year after the “Save Lake Windermere” campaign gained national attention when thousands took part in similar demonstrations.
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Mack and Coogan are taking part in the event in 2023 and have committed to playing a role in the event again this weekend.
The march began outside the United Utilities Information Centre at 10am, with supporters heading to the lakefront in Bowness.
There, speeches were given by representatives of the group Save Lake Windermere.
Mack and Coogan took part in a march on Saturday morning to officially launch the protests, but they are not the only celebrities to show their support for the movement.
The open letter by Save Windermere was supported by celebrities such as Chris Packham and Paul Whitehouse, as well as organisations including Campaign for National Parks, WildFish, The Countryside Charity (CPRE) and Wildlife Trusts.
This was sent to all political parties and demanded a commitment to further protect the lake and ensure its long-term health for future generations.
United Utilities has committed to investing around £20 million to reduce stormwater runoff into Lake Windermere early, aiming to start the work by 2025.
Water companies are building storage tanks in Ambleside, Elterwater and Hawkshead large enough to hold around 11 million litres of stormwater.
The Windermere project will increase storage capacity, allowing it to handle more sewage flow during heavy rainfall.
A United Utilities spokesman said: “The factors affecting water quality in Windermere are complex and without targeted action from multiple sectors we will not see the changes we all want to see.”
“We are doing our part by continuing to improve and enhance our operations and contribute to the overall health of Windermere.”