Police are keeping an “open mind” about the circumstances that led to the death of two youngsters who got into difficulty in the water off Bournemouth beach.

Joe Abbess, a 17-year-old boy from Southampton, and Sunnah Khan, a 12-year-old girl from Buckinghamshire, were rescued from the sea during the incident on Wednesday, but both died later in hospital.

Dorset Police said the beach was extremely busy at the time and they are continuing to appeal to witnesses to come forward.

They also urge people to submit any mobile phone or photographic footage to the police major incident portal.

Police have said that neither of the deceased young people or anyone else pulled from the sea at the time of the incident was involved in any collision or contact with any vessel in the water.

A man in his 40s, who was “on the water” at the time, was arrested on suspicion of manslaughter, and was released under investigation on Thursday.

Police said they are aware of “significant speculation” concerning a pleasure boat, which was in the area at the time of the tragedy off Bournemouth Pier.

The force said the investigation is looking at all circumstances of the incident including weather, wind conditions and the state of the water at the time.

As there was a pleasure boat in the area of water, this is just one of several lines of inquiry, police said.

The Dorset Belle sightseeing boat was impounded by Dorset Police after the incident.

Detective Chief Superintendent Neil Corrigan said: “We continue to keep an open mind around the circumstances that have led to the tragic death of two young people in the water off the beach.

“Our thoughts remain with the families of those young people.

“As with any investigation of this nature, we have to look at all factors connected to the state of the water.

“One of those lines of enquiry has involved the pleasure boat, which was in the area at the time of the incident. These enquiries also include examining wind, other weather and general coastal conditions at the time.

“We are working with experts from partner agencies to understand all of the factors and this will take time to establish.

“We continue to support the families of Joe and Sunnah and they are being kept updated by specially trained family liaison officers about our investigation.

“I would ask that the police investigation is allowed to continue without further unhelpful speculation around circumstances of the incident, and that there is respect for the families of those who have died so tragically.

“I would continue to appeal to anyone at the beach at the time who witnessed the incident to come forward and talk to us.”

Police said an inquest into both of the deaths is anticipated to be opened on Monday subject to confirmation by HM Coroner.

The family of Joe paid tribute in a statement saying: “We are heartbroken and devastated at the death of our Joe. He was a wonderful son and brother who is sadly missed.

“His family and friends will always love him and we are incredibly proud of the fabulous young man he was. He was kind and generous, loving and caring, hardworking and funny.

“Joe was a talented trainee chef, with a bright future ahead of him.

“We were privileged to have him in our lives for 17 years and we are so sorry he will never fulfil his dreams and ambitions.

“He was enjoying a day at the beach on Wednesday and we would like to thank his friends and all of the emergency services who helped him, when this tragedy unfolded.”

Dorset Police received a report from paramedics at about 4.30pm on Wednesday afternoon of people requiring assistance on the beach near to Bournemouth Pier.

Emergency services attended the scene and 10 people were recovered from the water, with eight of them being treated for injuries that were not life-threatening.