Sunderland Aquatic Centre was among 130 buildings affected by a power cut this morning.
Bosses of the complex said would be "closed until further notice" because of the lack of power, but has announced its lights are back on in the pool hall with lanes and open water now open to swimmers.
Power has also been restored in the gym, studios and reception, which are now open.
However, its phones are still off, with updates being issued through its Facebook page.
Traffic lights on Wessington Way have also been affected by the problem.
Northern Powergrid says it is aware of the issues and hopes electricity will be restored to the Southwick area by 10am, with 50 properties still affected.
It told customers: "We have restored power to some of the customers affected and continue to work to restore supply to the remaining customers
"The power cut affecting your property has been caused by an unexpected problem with the electricity cable that serves your area."
The problem was reported at 7am today.
For further information visit Northern Powergrid's website www.northernpowergrid.com.