Ilheus da Madalena

Two lava islets, Ilhéu Deitado and Ilhéu em Pé, rise from a submerged volcanic crater about half a nautical mile off Madalena harbour, and the dive works the basin between them: boulder fields and sand channels in compacted tuff rock. Official surveys and two catalogue listings put the crater floor at about 20 metres; one community dive log instead logs a shallower average of 10 and a maximum of 15. A swim-through threads the base of the taller, "standing" islet for divers who want it; the alternative is to go around. Visibility usually runs 10 to 30 metres. Inside the bay the water stays calm, but the current builds fast once you clear it into the open Faial-Pico Channel.

The two islets are the eroded remains of a single submarine volcano, and the dive circles the drowned crater between them, including the swim-through where the tuff of one islet has hollowed into a passage. The whole enclosed area carries formal protection: it sits inside the 6,689-hectare Canal Faial-Pico/sector Pico protected area, includes the Ilhéus da Madalena Special Area of Conservation and is named a priority marine geosite of the Azores UNESCO Global Geopark1. The Azores government also names the site as a reproduction area for grey triggerfish, and stingray colonies gather regularly around the crater. CW Azores runs it as a two-minute hop from its Madalena base, its go-to second-tank site, not a headline sell in its own right.

Current is the main hazard: calm inside the crater bay, but it builds sharply the moment you leave it for the open Faial-Pico Channel, and the site's own record calls for immense caution on the way out. Ferry traffic on the nearby Horta-Madalena route is a separate hazard. The swim-through is a short overhead section; divers who would rather stay in open water can go around the islet instead. Given the current and the swim-through, Advanced Open Water or equivalent experience is the safer call, even though the shallow crater bay itself would suit a newly certified diver.