A blaze caused severe damage at the Sovereign Centre on Friday night.
Firefighters were called at 6.23pm to the seafront complex.
A fire service spokesperson said, “We used two breathing apparatus and a hose reel jet to put out a small fire.
“A fan was used to clear the smoke.
“There were no reports of injuries.”
The fire was accidental.
A spokesperson at the Sovereign Centre said it did remain open over the weekend but there was disruption as the sauna and steam room were badly damaged.
“The sauna and steam room are out of action and there may be areas of the single sex wet side changing rooms affected causing minor disruptions,” said the spokesperson.
“We apologise for any inconvenience caused and we appreciate your cooperation at this time.”