Arcs del Dui

Drop down the buoy line into clear water and settle on the rocky shoulder around six metres. The first ten minutes are a calibration phase: buoyancy on a sloping reef, eyes on the small holes that pock the rock face, the kind of bottom where new divers learn that a Costa Brava wall is not a flat painted backdrop but a layered apartment block of moray, octopus, and small wrasse. Around twelve metres the first arch opens. The largest of the three is wide enough for a relaxed approach without snagging gauges or fins; light bends through the passage rather than disappearing, because these are short open-ended formations rather than roofed caves.

Past the arches, the slope continues to about twenty-five metres at the toe, with rock corridors flanking the path before they give way to coralligenous patches: small colonies of red coral on shaded faces, sponges, the occasional Paramuricea fan typical of Montgrí walls. Most centres turn here and work back along the wall a level shallower to extend bottom time. A 40-50 minute profile sits comfortably inside Open Water no-deco margins for the typical visiting diver. A torch helps inside the arches and pulls colour out of the deeper rock niches.

Most Costa del Montgrí sites a beginner can comfortably dive give you a slope and the marine life that finds it. Arcs del Duï adds one piece of geometry: three rock arches at recreational depth that you can swim through without overhead-environment training. That tighter pitch is why centres slot it into try-dive mornings, OW check-outs, and afternoon second dives. It is the relaxed end of a coast better known for the technical Cala Pedrosa tunnel, the deeper Reggio and Marmoler wrecks, and the tramuntana-proof Negre del Falaguer.

The marine-life texture is the second feature, in a quieter register. The wall sits in precoralligenous habitat — small holes and niches sheltering octopus, morays, forkbeards in shaded faces, sargos cruising the open water, and small red coral colonies on the shaded rock. The coralligenous community is fragile and slow-growing, which is the only real ask the site makes of a diver: hover off the wall, do not settle, and trim through the arches.

Bring a torch. The arches and the deeper rock niches both reveal more under a directed beam, and centres explicitly recommend one. Spanish recreational-diving law requires a dive computer and insurance — centres sell day cover. The site is inside the Parc Natural del Montgrí, les Illes Medes i el Baix Ter but outside the strict Medes Reserva Natural Parcial, so there is no diver quota, no permit, and no per-dive park tax for the coast. Anchoring on Posidonia is prohibited park-wide; centres use mooring buoys only.

The arches are open-ended swim-throughs, not cave penetrations — cave certification is not required, and the dive does not need overhead-environment training. Park cave rules still apply at the limit cases: small groups, no entry beyond natural light, no recreational diving past 30 m inside caves. None of those are practical concerns at Arcs del Duï's 12-20 m arch depth, but they explain why guides keep groups compact through the passages. If you are pairing the site with a Medes-islands dive, the reserve tax applies to the Medes leg only.