Boat operations from Bournemouth Pier have been suspended as a precaution following the deaths of two children.
Bournemouth, Christchurch and Poole Council said it had paused the activities while police continue to investigate.
It said the ban affected only one company which operates the Dorset Belle sightseeing boat.
The vessel was impounded by police after the deaths of Joe Abbess, 17, from Southampton, and 12-year-old Sunnah Khan, from Buckinghamshire.
An inquest heard a suggestion that a riptide led to the pair drowning.
Dorset Police said it was keeping an open mind about the incident last week and dismissed speculation the pair had jumped from the pier.
The force said it was considering causes including the impact of weather conditions and the state of the water.
The incident involved 10 swimmers on a day when the beach was packed during half-term.
The Marine Accident Investigation Branch has said no formal investigation has been launched but it was continuing to make inquiries.
A man in his 40s, who was 'on the water' at the time, was arrested on suspicion of manslaughter.
He has since been released while inquiries continue.
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