Almost 50 people were stranded for hours when a ride broke down at SeaWorld San Diego in the United States.

City fire spokesman Lee Swanson says 46 visitors and two park employees were on the Skytower when a power failure halted the revolving, climbing capsule as it climbed the tower and left everyone about 220 feet in the air.

The park says its officials were in constant communication and the employees in the Skytower provided water and snacks to the guests during the incident yesterday.

After four hours, power was restored and the ride descended shortly before 7.30pm local time.

No injuries are reported but Mr Swanson says a 17-year-old boy was treated at a hospital for anxiety.

The cause of the power failure is under investigation.