A controversial speed limit on England's largest lake is being introduced as planned on Tuesday.
The limit is being enforced using hi-tech speed cameras
Campaigners had urged the Lake District National Park Authority to halt the 10mph limit on Windermere, saying it would impact on tourism.
But the authority says it will make the lake a more tranquil place to visit.
Opponents say they have nowhere else to water-ski or use power boats, and that there was no real conflict between users and other holidaymakers.
The authority, which intends to enforce the limit by collecting evidence using digital video equipment, still cameras and a laser gun, believes it marks a new future for Windermere.
It says rangers will be on duty from Tuesday, but will not "chase" lawbreakers and risk lives. Those found flouting the law could be fined hundreds of pounds.
Campaigners, such as the Keep Windermere Alive Association, say they are bemused by the limit and that all is needed is a managed solution which would involve powered craft users being looked after by a governing body.
The bylaw was confirmed in 2000 following a public inquiry, but it was suspended for five years to give businesses time to adapt, according to the authority.