Arcos da Caloura

Caloura is a small fishing harbour on the southern coast of São Miguel, the largest island in the Azores, sheltered by a headland that has been carved by Atlantic wave action into a series of arches, tunnels, and sea caves. Arcos da Caloura — the Arches of Caloura — takes its name from these geological features, and the dive is structured around their exploration in what is one of São Miguel's most memorable underwater experiences. The site begins on volcanic basalt formations outside the harbour, where the rock drops in irregular steps and walls toward a bottom that ranges from twelve to twenty-five metres at this intermediate site. The basalt is colonised by the characteristic Atlantic encrusting organisms of the Azores: red and orange sponges, yellow and white anemones, the purple sea urchins that are ubiquitous on Atlantic rocky substrates, and the lime-green bryozoan mats that make Azorean rock look unlike anything in warmer seas. The arches themselves are the dive's focal point. Several natural tunnels and passages have been eroded through the basalt, large enough to swim through comfortably, and the swim-throughs provide one of the most memorable experiences in Azorean diving: emerging from the dim interior of a basalt arch into clear water on the other side, surrounded by shafts of filtered light. The walls inside the arches are particularly rich in organisms that prefer shaded, sheltered environments — feather stars extend their arms from crevices, and translucent sea squirts cluster on the rock in intricate formations. Fish life includes the typical Azorean cast: schools of amberjack patrolling in open water, the iridescent flash of ornate wrasse over the rock, and the inevitable common octopus in their stone-sculpted dens. Large dusky grouper — the impressive Atlantic grouper species — are reliable presences at this site, occupying prominent positions on the reef with the territorial confidence characteristic of their family. A wonderful introduction to the arch diving that makes São Miguel's coast so distinctive.