A comatose swimmer sank to the bottom of a tank in a terrifying underwater drama.

The mermaid performer reportedly passed out mid-show, shocking an audience and their children at Taiyuan Ocean World in Shanxi, China.

Harrowing footage shows the woman, wearing a colourful mermaid tail, lying face-down and motionless at the base of the aquarium on April 25.

Spectators initially believed it was part of the act. However, after around 20 seconds without movement, they grew alarmed and began calling for help.

A staff member wearing swimming goggles quickly dove in and struggled to pull the unconscious performer to the surface.

It reportedly took nearly two minutes before he managed to lift her head above water.

As the rescuer waited for assistance to remove her from the enclosure, he was seen balancing on a prop shipwreck while trying to keep her upright.

Local media reported that the performer was rushed to hospital and placed under observation.

A spokesman for Taiyuan Ocean World said that the woman was hypoglycaemic and had fainted due to low blood sugar.

The theme park announced the suspension of all performances to conduct a safety inspection.

Hypoglycaemia occurs when blood sugar levels drop too low, depriving the brain of energy. This can lead to dizziness, confusion, or fainting — especially during physically demanding tasks.