Humberside Police have received reports of what is believed to be a body in the Humber estuary.
The force said: "A report was received at around 1.45pm on Tuesday, February 26, of what was believed to be body in the water close to the ferry terminal in Hull.
"Our teams are currently working with the Coastguard and Search and Rescue in and around the area."
Teams continued to search the estuary but police said later there had been no further sightings.
A statement said: "Following third party reports of what was believed to be a body earlier this afternoon close to the ferry terminal in Hull, various teams and units were deployed and continued searching the Humber until around 7.15pm this evening.
"Extensive searches were carried out with assistance from the Coastguard, NPAS and Search and Rescue teams, however there have not been any further sightings."