Park Manager Jon Allred says people nearby witnessed the incident and saw that the man had not emerged from the water.
At this point, a bystander went in and pulled the man out, who was reportedly not breathing. Someone with training then performed CPR on the man, officials say, and he regained breathing.
A LifeFlight helicopter then arrived and took the man, who was still unconscious despite being able to breathe, to the St. George Regional Hospital.
Officials say the condition of the man is currently unknown.
The age or identity of the man have not been released at this time.
No further information is currently available.