Kalymnos is a bare limestone island, separated from Leros, by the narrow channel of Stenon Lerou. The coasts are mostly steep and rocky, with numerous coves and inlets ideal for a sailing holiday. The inhabitants live partly by farming in the few fertile valleys, but mainly by fishing for sponges in the south-eastern Med and processing them for export to the USA. The departure (April-May) and return (Sept-Oct) of the sponge-fishing fleet are celebrated with lively festivities. Sponge fishing means a yearly excursion and every spring the sponge-fishers of Kalymnos cast off for the seas off the North African coast. Their departure is a moving and important event, which is therefore accompanied by fancy religious ceremonies. After approximately five months of hard work the sponge-fishers return to the island.

Finds in various caves round the coasts, particularly near Vathy port, show that Kalymnos has been continuously inhabited since the Neolithic period. The island never played a prominent role in history. From a distance Kalymnos town, formerly called Pothia, the monastery on the hill and the shining cupola of the cathedral can be seen.
The town, its handsome houses, in the neo-classical style popular in the islands in the 19th century, rises above the harbour on the gentle slopes fringing the bay. North-west of the town is the former capital of the island, Khorio (17th century), with a Byzantine castle. Halfway between these towns stands the Frankish stronghold of Pera Kastro.