The island of Vis (Lissa in Italian) lies in the middle of the Adriatic Sea, along the Croatian coast. This island is one of the best spots for diving of the Adriatic, with clear crystalline water and fantastic wrecks to be discovered. The dives range from easy recreational until deep technical because of the depth. I already spent two summer vacations in this little mountain rising from the sea in the nice village of Komiža.
The best dives are usually characterized by wrecks, like the Teti (-10 to -35m), the Vassilios (-30 to -51), the B24 (-40 m while the tail of the airplane lies at -52m), the Fortunal (-56m). Shallow reef dives are also present, especially on the NW edge of the island at Šika 6 or in the shallow caverns along the SW coast. There are basically dives for all the different levels of diving: the only thing to remember is that the water is relatively cold, even in August, with 16 degrees celsius at 25 m of depth.
Luckily, around this island there is still a lot of fish, especially sardines, but is also common to see dolphins, congers and moorays, more rarely Mediterranean parrot fish, the St Peter, lobsters, etc. Many walls are plenty of gorgonians and sponges, with an outstanding biodiversity.
There are several diving centers in the island, but I prefer to go to the B-24 diving center, owned by the Croatian freediving champion Veljano Zanki: the environment is very friendly and very professional, perfect for a diving holiday. They can also fill tanks with nitrox and trimix without any problem.