A man and a woman believed to be under the influence of alcohol fell off the quay near Haven Bridge, Great Yarmouth, landing on a boat.
The Gorleston and Great Yarmouth RNLI assisted in the rescue of the couple, who had fallen 9ft from the sea wall.
The RNLI lifeboat Atlantic arrived at 7.32pm to assist other rescue services, who had been unable to reach the couple from the sea wall.
Police were called at about 7.45pm on Friday but had to mobilise firefighters when it became clear one of them had injured his back.
The man, who was unconscious, was lifted on to the quay and taken by ambulance to James Paget University Hospital, Gorleston.
Volunteer crew member and trained paramedic helmsman Rod Wells was one of the first onto the boat.
He said he understood that the female suffered no injuries but the man is currently in intensive care at the James Paget Hospital.
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