It is not enough to say that in the waters surrounding the island of Vis every diver will find sites particularly interesting for him. There are several places suitable for the beginners as well as a few real treats for technical divers. In some places the sea is always calm, with no waves and currents, and gripping objects can be found on shallow depths. On the other hand, there are wrecks located deeper than 40 m below sea level and caves and caverns demanding advanced diving skills. Moreover, the diving sites can be divided into different groups basing on types of these sites, not only on the depth and difficulty. Four groups can be distinguished: natural sites, archaeological sites, caves and caverns and wrecks.
The first group – natural diving sites – consists of walls full of life, slopes with different angles of inclination and several places where enormous rocks create corridors through which the divers can swim. Walls are usually almost vertical. From the surface to a depth of about 10 m there are lots of small fish playing, deeper the divers can find numerous crustaceans hiding in the holes, moving bearded fireworms and nudibranches belonging to various species. Natural diving sites are the most impressive during the night dives, when all the nocturnal animals are hunting. Although there is plenty of light under the water during the day dives, it is good to use torches. First of all, to be able to spot organisms in the holes, secondly to bring out natural colours of deep water organisms, like red sea fans. Due to disappearance of warm pigments, the yellow sponges, abundantly covering rocks at a depth of about 40 m, are fluorescent.
Mentioned yellow sponges are typical inhabitants of the entrances to caves and caverns. In the entrances, on the border of light and dark, there are also living numerous crustaceans, like spiny lobsters, squat lobsters and spider crabs. Caves and caverns differ in shapes and sizes, but can be found almost everywhere around the island of Vis. Small caverns with spacious entrances, suitable for the beginners, are often located at the depths of a few meters. Although in such caverns daylight can be always seen, the divers have to keep in mind that they are visiting overhead environment and that they need to keep neutral buoyancy, because the bottoms of caves and caverns are always covered by sand or silt. Besides, there are a few caves requiring advanced skills. There, in the dark, thousands of shrimps can be found. There, as well, occur unexpected phenomena – in one cave there is a thermocline and a halocline at a depth of 6 m above which water loses on temperature and salinity.
As the underwater walls, slopes, caves and caverns are natural forms, there are also different artificial objects adapted by sea life. To such objects definitely belong amphorae – the remains of ancient times. A few thousands years ago the island became the first Greek colony on the Adriatic Sea. Then it got under the rule of the Roman Empire and for years was the most important commercial port of the Adriatic Sea. Numerous ships were passing the island and some of them crushed in the surrounding waters, hitting unmarked islets. After those wooden vessel left nothing by the cargo – amphorae in which wine and olive were transported. After long years these amphorae are abundantly covered by colourful sponges and inhabited by octopuses, painted combers and hermit crabs.
It occurs that younger objects, not having archaeological meaning, are also attractive for marine life. It is even hard to imagine a steel wreck without its inhabitants, among which should be listed inter alia scorpionfish, forkbeards and moray eels. Around the island of Vis there are a few wrecks from the 20th century. Some of them, like a fishing boat Fortunal, crashed by accident, but several are historically important. Among those, there is an Italian tugboat Ursus and two airplanes belonging to American Air Force – the Boeing B-17G Flying Fortress and the B-24 Liberator. Although the time of World War II has left its mark on the history of the region, it also somehow contributed for the touristic attractiveness of the island of Vis, specially for the advanced and technical divers, who can admire historical objects under the water.