Eight lockers were ransacked by a thief who ripped off padlocks and stole jewellery, cash, clothes and car and house keys.
Police are appealing for witnesses to the thefts, which took place at the David Lloyd leisure centre some time between 12pm and 3pm on Monday (May 27).
The incident follows a similar raid on May 2, when 10 lockers were broken into.
PC Rachel Bourne, of the Eastbourne North Neighbourhood Policing Team, said, “I would urge David Lloyd members to be extra vigilant and report any suspicious activity to staff immediately.”
Any witness or anyone with information is asked to call 101 quoting serial 1426 of 27/5. Alternatively, call the independent charity Crimestoppers anonymously on 0800 555 111.