No boat was involved in the deaths of two young swimmers next to Bournemouth pier, investigators said.
The Marine Accident Investigation Branch (MAIB) said it has decided not to carry out a full inquiry into the incident on May 31 following a “thorough preliminary assessment”.
Joe Abbess, 17, and Sunnah Khan, 12, drowned and eight other people were treated by paramedics after they were suspected to have been caught in a riptide next to the pier at the Dorset seaside resort.
Dorset Police impounded the pleasure cruiser Dorset Belle at its berth in Poole Harbour following the fatal incident.
The MAIB said in a statement: “Having conducted a thorough preliminary assessment of the circumstances of this tragic accident the MAIB has decided that no formal investigation will be launched.
“This was a truly tragic accident but our understanding of the circumstances is that it did not involve a vessel and therefore is not something the branch would investigate.”
A man in his 40s, who police said was “on the water” at the time, was arrested on suspicion of manslaughter and later released under investigation.
Bournemouth, Christchurch and Poole Council suspended boat operations from the pier.
An inquest into the deaths of the two youngsters, which was opened at Bournemouth Town Hall earlier this month, heard that they were part of a group of people thought to have been caught up in a riptide in the sea near the pier.
Post-mortem examinations found that they both died of drowning, the inquest was told before coroner Rachael Griffin adjourned proceedings to a further hearing in September.
Dorset Police said the beach was extremely busy at the time of the incident but that neither of the youngsters nor anyone else pulled from the sea had been involved in any collision or contact with any vessel in the water.
