The underwater and specialist search unit were called out to Mansfield today after a man reported a 'suspicious' object in the water.
The Nottinghamshire Police Unit responded to a stretch of the Maun River off Ravensdale Road.
A concerned resident said: "Something is going off, there is a big police van and four police men in wet suits."
Police have said nothing 'unusual' has been uncovered.
A spokes woman from the force said: "At around 10am today, Thursday, March, 8, we received a call in good faith from a man who'd been fishing in the river Maun in Mansfield and believed he'd seen something suspicious in the water.
"Our underwater search team have been down to the location but nothing unusual has been uncovered."
The team are currently still in the river.