Croatia
Croatia's premier wreck-diving island, ringed by WWII aircraft and shipwrecks, plus the famous Blue Cave on neighbouring Biševo and the Green Cave on Ravnik islet.
Vis was a closed Yugoslav military zone for decades, leaving its coastline and surrounding islets comparatively undived and rich in marine growth. It hosts multiple WWII wrecks, including a B-17 Flying Fortress near Cape Polivalo, the B-24 Liberator 'Tulsamerican' near islet Paržanj, and the steamships Vassilios T., Ursus and Teti. Reef and wall dives include Sika 3 and Sika 6 off Komiža Bay. Nearby Biševo island holds the Blue Cave (Modra Špilja) in Balun bay, a flooded sea cave known for its blue light effect; public swimming/diving inside is prohibited but surrounding waters are dived. Ravnik islet's Green Cave (Zelena špilja) is a similar sea cave. Source: Wikipedia (Vis, Blue Grotto Biševo), DAN, scubadiving.com.