The first Greeks to work on sponge diving were the inha bitants of Symi. They have taught the other islanders to dive, process, and trade the sponges. The foreign travelers who visited Greece in the Middle Ages, as only the i nhabitants of Symi fetched sponges, believed that sponges occur only on the soi l of Symi. In 1840, the first diver from Symi Michael Karanikis dived at the bottom of th e sea, holding a flat stone weighing about 12-15 kilograms.
This stone, which la ter became known in Simi “kampanellopetra” or “Skandalopetra” in Kalymnos, was tied at one end with a rope and the other end was tied by boat. The sponges broug ht wealth to the islands. In 1863, the Symiote Photis Mastoridis brought the divin g bell (Skafander) from India to Symi, where he worked with the English in port works. To convince the Symiots of the usefulness and safety of the diving bell, his w ife Eugenia used it to dive with for the first time, in the port of Symi. So since 1863 t he first use of a diving bell has been made in Symi. In 1864 it was put into operation in t he other islands of the Dodecanese and from 1866 on the other Greek islands. From 1863 to 1896, the number of boats with diving bells over the Mediterranean reached about 440, while the number of ships of nude divers steadily decreased.
Simi had the world’s largest sponge-diving fleet and was a pioneer in sponge diving on the North African coast, processing the sponges and marketing them through the island of Syros to London and the United States. At the forefront of this vital industry was t he company from Symi, the sons Nikita Petrides were known abroad as Petrides brothers, w ith offices in Syros, Piraeus, Paris, and London.
With the significant turno ver of the great benefactor of Symi George Petrides, the Clock Tower was built, the Petrideion School and the magnificent Classicist buildings on both sides of th e Government Building. The Italians, later rulers of the Dodecanese, banned sponge diving during the First World War, which led to a gradual decline in the populatio n of Symi. So slowly Kalymnos began to take the first place in sponge diving.