Blue Hole
Depth is the range from the top of the site to its usual maximum; "recommended cert" is the mainstream-agency level operators usually ask for, not a legal rule. Currents and visibility change daily — treat everything here as planning ranges.
Gozo's Blue Hole is the Mediterranean's most famous ten meters of water: a sheer-sided pool in the Dwejra limestone that funnels divers down to an archway at about 8 m and releases them onto open blue wall. Since the Azure Window collapsed in a March 2017 storm, the seaward slope holds its enormous remains — clean-edged blocks the size of buildings, already colonizing with algae and schooling damselfish, a dive now known as Azure Reef. A chimney through the rock and the small cave at the hole's base complete the circuit. Mornings belong to divers; by mid-day the pool doubles as the local swimming hole.
The moment you come for: The archway exit into blue, Azure Window boulder field, chimney swim-through
Topography: A collapsed limestone sinkhole opening through an underwater archway onto walls and the tumbled remains of the Azure Window
Entry: A walk across Dwejra's fossil-studded limestone shelf to a natural rock pool entry; boots and calm seas make it comfortable, and swell makes it unwise.
Know before you splash
Hazards: Swell surges through the entry pool and archway in anything but calm weather; boulder terrain drops quickly past 30 m.
Conservation: Within the Dwejra protected area; the collapsed Window's stone is part of the site's story and stays untouched.
For photographers
Wide angle: ★★★★★ · Macro: ★★☆☆☆ — editors' 1–5 rating of what this site gives each style of shooting