The girl, Hayley Liane Williams, was pronounced dead on arrival at hospital after falling 100 feet from the park’s signature Hydro ride into a splash pool below.

A 10-year-old boy, who was on the same ride, was also injured.

The £2m, Swiss-built Hydro ride, described by Oakwood as ‘Europe’s fastest and wettest water coaster’ and introduced to the park in 2002, measures 121ft at its highest point – just 34ft lower than the Niagara Falls.

Dyfed-Powys Police and the Health and Safety Executive have begun investigating the death, while the Hydro ride will remain closed in order for forensic examinations to be carried out.

Oakwood Park, which opened its doors for 2004 on Easter Monday, will stay open during the investigation.

Dyfed-Powys Police are requesting anybody who visited the Oakwood Leisure Park on 15 April and may have witnessed the incident to contact the incident room at 01437 771709 or 01437 771710