The pool at Grimsby Leisure Centre, has been temporarily closed due to a burst water pipe.
North East Lincolnshire Council has deployed specialist engineers to inspect the site and the pool will remain closed until further notice.
All other services at the leisure centre are open as normal.
Sue Wells, assistant director for culture, leisure and sport, said: "We apologise for any inconvenience caused to customers. Given the age and condition of the building, incidents such as this are unfortunately unforeseeable, demonstrating the need for new pool facilities.
"We are working closing with contractors to ensure work is completed as soon as possible."
Alternative provision for swimming lessons has been made at Grimsby, Cleethorpes and Immingham Swimming Pools.
Customers are being contacted directly. These swimming pools will also be open over the weekend for leisure use.
