Kalymnos is known as the "Sponge-divers' island". Sponge diving has long been a common occupation on Kalymnos and sponges were the main source of income of Kalymnians, bringing wealth to the island and making it famous throughout the world. The Kalymnians harvested sponges from the sea-bed as close as Pserimos or as far as North Africa. Early diving was done without equipment (free diving), using a rock. Sponges are still fished individually, by hand.
The Greek sponge trade was centered close in the Dodecanese, featuring Kalymnos until mid-80s, when a disease hit the eastern Mediterranean destroying a great number of sponges and damaging the sponge-fishing industry as a result. Today, Kalymnos faces a lack of sponges due to the outbreak of a disease which has decimated sponge crops.
An annual celebration, Sponge Week, occurs a week after Easter to honour this "Kalymnian gold.” Much has been written, sung and filmed about the legendary courage and recklessness of the sponge divers themselves.