Narrow boat owners have been blockading canals across England as part of protests over cuts to the government grant given to British Waterways.
Canals in London, central Birmingham and Manchester were among those blocked by Save Our Waterways' protesters.
Protesters say the £7m cuts would affect canal maintenance while Unison workers say the cuts would lead to 180 jobs losses by April.
Defra has said investment in waterways has been "heavy" in recent years.
It also said it was "confident" British Waterways would be able to carry on with its job.
Union leaders are meeting Labour MPs to protest against the cuts.
Boat users, ramblers and cyclists were also expected to join protests, while blockades were planned on canals on waterways including, in Gloucester and Northampton.
The Save Our Waterways campaign claims further cuts to the waterways budget are planned over the next five years.
Unison spokesman Chris Fabby said: "In the run-up to Christmas, 180 hard-working, loyal British Waterways employees face the nightmare prospect of losing their jobs through no fault of their own.
"We have made it clear to British Waterways that any attempt to implement compulsory redundancies will be met by a wave of protest by workers and the unions.
"However, if British Waterways is successful in clawing back any grant money, we want a commitment that it will be used to eliminate, or at the very least reduce, the number of planned job cuts."
Ivor Caplin, of the Inland Waterways Association, said: "The inland waterways are over 2,000 miles of canal and river, many of which are over 200 years old, they're very frail and part of our heritage and they have to be maintained to the right level.
"There needs to be continuous, ongoing maintenance. It's a case of a stitch in time, really."
Matthew Corbett, a former star of the Sooty and Sweep show, is now a narrow-boat enthusiast who joined the protest in Manchester.
He said removing the money was "just so short-sighted".
"Manchester has been regenerated mainly because of the waterways," he said. "There's blocks of flats. There's so much money involved. If you remove the money, it's like taking blood away from the heart."