Cromer lifeboat was called into action after people in a helicopter reported seeing a life vest and fluorescent marker in the sea.
An officer at Humber Coastguard operations centre received the call about the sighting off the coast near to Cromer at 4.21pm today.
A stand-by vessel was deployed and the Cromer lifeboat was later launched.
Nothing was found, and crews were stood down at 5.37pm.
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