Humber Coastguard was called at around 12.34pm while Norfolk Police and paramedics arrived at the scene at around 4pm.
There are reportedly four lifeboats involved in the search as well as a helicopter.
A spokeswoman for Hemsby Lifeboat helm, said: “We are still doing a search of the area, a boxed search.
“The last known location is two to three nautical miles offfshore at Hemsby Gap.”
