Members of the oldest remaining river swimming club in England are fighting for wider rights to access the water.
Rob Fryer, of the Farleigh and District River Swimming Club in Somerset, wants greater freedom to swim in rivers.
Campaigners have called for a new blanket law for river access similar to the countryside "right to roam" act.
But a spokesman for the Country Land and Business Association (CLA) said the current system of voluntary negotiated access arrangements was working.
Mr Fryer, who is chairman of the club, said swimmers were regularly running the risk of trespassing as traditional river swimming spots were being closed off to the public.
"The law over access at the moment risks turning people like me into rebels," he told the BBC's Inside Out West programme.
"All too often there are restrictions, there are notices or there's barbed-wire and you can't actually access it and so there's these places where people used to swim and they're no longer able to. I think it's tragic."
Mr Fryer said one spot on the River Frome, where the club is based, had been recently fenced off despite it being used by villagers for years.
But local landowners claim people swimming at the spot near Freshford Weir have been responsible for vandalism and litter.
Paul Millard, of the CLA, said no private riparian landowner should be forced by law to give the public access to the river.
He said: "It's a question of balance. We have to get the balance between who is using what part of the countryside for what and that's best done by voluntary agreements.
"In our opinion going to government and asking for compulsory access is really taking a very large hammer to crack what's a very small walnut."