Emergency services are on the scene of an incident at Hartlepool Marina.
They were called out on Friday afternoon after reports a person was seen in the water.
A spokesman for the North East Ambulance Service said: "We were called to an incident at Hartlepool Marina at 1.30pm.
"We sent one rapid response and one double-crewed ambulance."
A Cleveland Police spokesman said: "We were called following concerns for the welfare of a woman."
We will bring you more on this story as we get it.