Spot checks at hotels, rented rooms and other tourist resorts on islands near Athens revealed that 80 percent of the sites had swimming pools that were operating without a proper license. Piraeus Prefecture officials found that 24 of the 30 swimming pools they checked did not have the necessary paperwork and ordered them to be drained. Ten of the pools were on Spetses, six on Aegina, four on Poros, three on Agistri and one on Hydra. The officials also took samples of water from the pools to send for tests in Athens. Swimming pools have to fulfill a number of criteria, mostly to do with safety and hygiene, before they are awarded a license. The prefecture has written to the Greek National Tourism Organization asking for licenses to be issued to the resorts whose pools comply with the regulations.