Malta
Gozo is widely regarded as one of the top diving destinations in the Mediterranean, famous for the Dwejra cave/tunnel complex (Inland Sea, Blue Hole, collapsed Azure Window) and scuttled wrecks at Xatt l-Ahmar.
Wikipedia states Gozo 'is considered one of the top diving destinations in the Mediterranean'. Its Dwejra area contains the Inland Sea, an 80m tunnel to the open sea, and the Blue Hole sinkhole dive site. The adjacent Azure Window, a natural limestone arch, collapsed into the sea on 8 March 2017; its submerged remains are now dived as 'Azure Reef'. Gozo's south coast (Xatt l-Ahmar) has deliberately scuttled wrecks: MV Xlendi, MV Karwela, MV Cominoland and MT Hephaestus. Source: Wikipedia (Gozo), PADI, Scuba Diving magazine, maltadives.com, blueholediving.com.