REPORTS of a man splashing and calling for help in water off Southsea Common sparked a three-hour search.
Gosport and Fareham Inshore Rescue Service hunted for the missing man off Portsmouth but found no-one.
The coastguard sparked the alert at 1.27am but the search was scaled back and ended at 4.20am.
It is not known what happened to the person.
Gafirs’ lifeboat, inshore lifeboat, Land Rover and rescue mobile were all used in the search, along with the coastguard’s helicopter based in Lee-on-the-Solent.
Portsmouth and Hill Head coastguard and Hampshire police’s marine unit were also involved in the search.
After an extensive and saturated air, sea and land searching by all the units the decision was made to stand all units down until further information comes to lightCoastguard spokesman
A coastguard spokesman said: ‘They were tasked to reports of a person in the water at Clarence Esplanade.’
‘After an extensive and saturated air, sea and land searching by all the units the decision was made to stand all units down until further information comes to light.’
Night vision equipment and search lights were used to search from the Harbour entrance to Southsea Castle.
Clarence Parade Pier was also searched extensively.
Gafirs senior coxswain Chris Rudd said: ‘After a major search lasting several hours nothing was found.’