Liquid Leisure Windsor brands itself as the “world’s number one” water sports and activity park and the largest aqua park in Europe.
But today, it is understood to have been evacuated once the search for the girl began.
One Twitter user who planned to visit the park today claimed a child had gone missing, user @irxheem said: “Was about to start a session at Windsor Liquid Leisure at there was announcement that a girl has gone missing, they don’t know if she is missing in the water.
“Really really pray that they find her.”
Express.co.uk contacted Berkshire Fire and Rescue who refused to comment.
We have also contacted Thames Valley Police who is yet to provide any information on the incident.
South Central Ambulance Service was also contacted for further information.
Berkshire Lowland Search & Rescue say its teams have not been drafted in to help look for the girl.
An RNLI spokeswoman also told Express.co.uk it had not been called.