WA Police say just before 8am they were advised a person on a jet-ski had been struck by a king wave and had come off the ski.
At 10.43am a police spokeswoman said Marine Rescue Two Rocks assisted and the male rider was taken to hospital by St John WA with possible spinal injuries.
At 10.59am a St John WA spokeswoman said a man in his 30s had been transported (with spinal precautions) by road to Royal Perth Hospital (RPH).
She said he arrived at RPH at 10.19am.
