Arena

Arena is Manta Diving Madeira's house reef at Caniço de Baixo, inside the Garajau Marine Reserve on the island's volcanic south coast, and the water starts only a short walk from the base. Divers pass a golden sponge worked by trumpetfish and schools of bream before reaching the reef's centrepiece two ways: down through an opening in the reef roof and along a tunnel, or directly from open water. The tunnel is light-flooded and drops into a vertical chimney inside a single pinnacle, whose arches and walls give the site its name and its nickname, the amphitheatre. Outside, a large cascade formation offers another vantage point on the way out. Groupers, barracuda, moray eels and the island's round stingray work the same ground, alongside occasional mackerel and slipper lobsters tucked into the tunnel's cracks. One independent account also lists a boat approach to the same reef, though the confirmed, everyday way in is on foot from the shore.

Against its Garajau-cluster neighbours, one built around a resident moray in a small cave and another around a pair of volcanic pinnacles, Arena's differentiator is architecture, not a marine-life superlative: the pinnacle-and-tunnel form is what both the operator and an independent search lead with. One underwater photographer who has shot the site since the early 1990s calls it, in his own words, "an amphitheatre built by human hands, hidden beneath the sea." The site is also built for two levels of diver: a shallow route to about 12 metres carries Discover Scuba Diving and Open Water divers past the entrance sponge, while the tunnel-and-chimney route to the site's deeper working maximum suits Advanced divers. Descriptions of the fish life vary from one visit to the next: some dives are rich with schooling fish, others come back thinner, so treat abundance as variable, not a promise.

The tunnel and chimney are an overhead swim-through: hold trim through the passage and control your ascent inside the chimney instead of heading straight for the surface. Currents run along this stretch of the reserve coast and are usually mild, but check with your guide before entering the tunnel on a livelier day. Like the rest of Garajau, spearfishing gear is banned here and an unescorted group of divers is capped at eight, marked with a buoy; the reserve's 1997 diving regulation prices unpaid amateur diving only, so a guided trip's cost sits outside that figure. South-coast shore entries in the reserve also meet open Atlantic swell, so time your entry and exit between sets.