North Yorkshire Police, Yorkshire Ambulance Service and the coastguard could be seen on Scarborough's north bay this morning.
An abandoned jet ski could also be seen on the beach.
It is understood the incident happened at around 8am.
A spokesman for the Humber Coastguard said a male jet ski rider had been injured and taken to hospital.
The full extent of his injuries are not known.
North Yorkshire Police would not give any details.