Malta

A natural vertical shaft in limestone at Dwejra Bay, Gozo, connected to the open sea by an archway from ~6m to ~15-18m — Malta's single most famous, most-photographed dive site. Open Water certification (18m limit) suffices for the arch itself; the adjoining outer wall drops much deeper (40-50m per some listings) and needs Advanced-level training, but that describes the surrounding wall, not the core swim-through. Shore-accessible via steps cut into the rock, no liveaboard.

A 110m Libyan oil tanker, deliberately scuttled off Wied iż-Żurrieq in 1998 after a fatal 1995 engine-room explosion took her out of service. Sits upright, funnel at ~15m, stern/propeller at ~36m; a 2005-2006 storm broke the wreck into two sections. Advanced Open Water certification (to 30m) is the stated minimum; Wreck Diver certification is additionally required for interior penetration. Shore-accessible via a short jetty swim, no liveaboard.