Swimmers, kayakers and rowers will gather and circle round salmon sites in the Sound of Jura, Firth of Lorn and Loch Linnhe in Argyll, gathering effluent samples to test for viruses, pathogens, chemicals and contaminants in the water.
The campaigners are calling for greater scrutiny of the country’s aquaculture industry, which has been coming under increasing pressure over its impact on nature.
Many of the protesters will be in costume - including a salmon, a lobster in a gas mask, a porpoise in ear defenders and a seal in a bullet-proof vest - to highlight some of the issues surrounding salmon farming.
Fish farming is worth around £1 billion to the Scottish economy, with salmon the country’s top food export.
But persistent problems with fish health and environmental pollution have blighted its image in recent years
Scottish ministers have laid out plans to double production, currently around 160,000 tonnes a year, by 2030.
The move has sparked outrage among environmental and fisheries groups, who believe open-cage fish farms are harming the marine ecosystem, causing animal suffering and wiping out wild salmon.
A Scottish parliamentary inquiry into the environmental impacts of the industry was carried out but found "insufficient evidence" to support calls to halt expansion.
Now nearly 44,000 people have signed an online petition calling for the Scottish Government to carry out immediate unannounced inspections of all fish farms in the country to assess their fish welfare and environmental standards.
“It is time for people to reclaim the seas from the filthy floating factory fish farms which are polluting our coastal waters, destroying our wildlife and turning the king of fish into the marine equivalent of battery hens,” said John Robins, from Scottish campaign group Animal Concern.
“Salmon farming is unsustainable, incredibly cruel and very damaging to the marine environment.
“The Scottish Government must take the lead from the protesters and act now to stop salmon farmers destroying our coastal ecosystem.”
Don Staniford, director of the campaign group Scottish Salmon Watch, said: "Salmon farming in Scotland is dead in the water.
“If consumers could see the shocking welfare abuse and disease-ridden nature of factory fish farms they would be horrified.
“Scottish salmon is ethically and environmentally repugnant and should be avoided like the plague.”
Dennis Archer, co-convenor of the Argyll and Bute branch of the Scottish Green Party, said: “Argyll needs to treat its marine environment better and will get no help from the Scottish Government in Edinburgh.
“There are better ways of managing this polluting industry without the chemicals, with more jobs and bigger benefits to the Scottish economy. The first thing people can do to help is to stop eating farmed salmon.”
But industry leaders have warned demonstrators not to get too close to fish farm operations.
Hamish Macdonell, director of strategic engagement for the Scottish Salmon Producers Organisation, said: "Unauthorised visits to fish farms place employees and the animals they care for at risk.
"They also pose serious hazards to those entering the farms without permission. As a result, any visit must be undertaken in accordance with the strict safety and biosecurity measures in place on each farm and take place only with the express permission of the farm manager.
"Salmon farmers ask that people remain a safe distance away from farms and other facilities, for the safety of all involved and to protect the health and welfare of the livestock."