Members of the public helped search a lake before the girl was found by emergency services.
Image source, Getty ImagesAn 11-year-old girl has died after getting into difficulty at a water sports and activity park.
Police, fire and ambulance services were called to Liquid Leisure Windsor in Datchet, Berkshire, at about 15:55 BST on Saturday.
The girl was found at 17:10 BST after a search of a lake and taken to Wexham Park Hospital.
Thames Valley Police said her death is being treated as unexplained and an investigation has been launched.
Supt Michael Greenwood said: “This has been an extremely traumatic and upsetting incident for all involved.”
Several members of the public got into the lake shortly after she got into difficulty “but were unable to locate her”, he said.
“I would like to commend them for their courage and bravery.”
The Royal Berkshire Fire and Rescue Service, Buckinghamshire Fire and Rescue Service, Surrey Fire and Rescue Service and South Central Ambulance Service joined police officers at the site.
The National Police Air Service was also involved in the search.
The girl’s next of kin have been informed and they are being supported by officers.
Supt Greenwood, the local policing area commander for Windsor and Maidenhead, offered his “sincere condolences” and requested that the privacy of the girl’s family be “respected”.
He said: “We are in the early stages of investigating this incident to understand the full circumstances.”
On its website, Liquid Leisure Windsor describes itself as being home to Europe’s largest aqua park with activities including wakeboarding, a floating obstacle course, open water swimming and boat rides.
In a statement on its Facebook page, the company said it will be closed on Sunday.
It said: “Our thoughts and prayers are with the family, friends and all those effected by this desperately tragic and upsetting incident.”
Liquid Leisure Windsor added it would not be right to comment further while police are in the early stages of an investigation, but it would “continue to fully support and assist them throughout the process”.