If you are interested in something else then Korčula we can take you to:
Dubrovnik along the way you can take a swim on Elaphiti islands (Šipan). Hvar along the way to have swim on Paklinski islands (Palmižana). Vis to explore and swim inside Blue Cave on Biševo or Budikovac with turquoise lagoon. Lastovo nature park which has Pasadur, lighthouse Struga, military tunnels from Yugoslavia and many places to take swim.
Price for any of these excursions is 500 euro + fuel
Snorkeling equipment and cold drinks on boat are included in price