Arcos da Caloura
37.7167°N 25.5000°W · cave
Arcos da Caloura
An impressive lava cave system with four underwater entrances — the ceiling is packed with dozens of nudibranch species, making it one of the Azores’ best macro sites.
Overview
Arcos da Caloura is a cave system on São Miguel’s south coast formed by ancient lava flows, situated only 300 metres from the coast in a sheltered bay. The reef top starts at 5 metres, dropping to 18 metres at the deepest cave entrance. There are four underwater entrances to the cave, the main one at 16 metres. The well-lit passages make this a welcoming cave dive despite its classification as a cave environment. Access is by boat only (15 minutes from Vila Franca do Campo Marina; 30 minutes from Ponta Delgada).
The cave ceiling is covered with dozens of nudibranch species, making it one of the best macro diving sites in the Azores. Inside the cave, schools of large white trevallies and resident dusky groupers are regularly encountered.
Site Information
- Location: Caloura, south coast São Miguel, Azores
- Entry Type: Boat dive
- Site Type: Cave/cavern
- Difficulty Level: Intermediate
- Maximum Depth: 18 meters
- Typical Visibility: 15–25 meters
- Current: Weak
- Best Time: May to October
Marine Life
Inside the cave: schools of large white trevallies, resident dusky groupers (Epinephelus marginatus), and a ceiling packed with nudibranchs of many species. Outside: moray eels, Guinean puffers, Mediterranean rainbow wrasses (Thalassoma pavo), wide-eyed flounders, ornate wrasses, salema porgies, Azores chromis (Chromis limbata), parrotfish (Sparisoma cretense), and blacktail combers (Serranus atricauda).
Tips and Recommendations
- The cave ceiling covered in nudibranchs is one of the Azores’ best macro sights
- Four underwater entrances — well-lit and suitable for divers who have not done cave dives before
- Access is by boat only — not a shore dive despite proximity to coast
- Also excellent for night dives and snorkelling (reef top at 5 m)
- 15 minutes from Vila Franca do Campo Marina, 30 minutes from Ponta Delgada
Sources: dive.visitazores.com, Portugal Dive, Scuba Diving Magazine – Azores Guide. Last updated 2026-07-17.
Sea-surface temperature and wave height from Open-Meteo Marine (ERA5 reanalysis, monthly averages).
19184 verified species observations (37 species) logged within ~11 km of this site between 1963 and 2025, from the Ocean Biodiversity Information System.
- Delphinus delphis
- Tursiops truncatus
- Physeter macrocephalus · Sperm whale
- Stenella frontalis
- Grampus griseus
- Balaenoptera physalus
- Balaenoptera borealis · Sei whale
- Stenella coeruleoalba
- Sterna
- Calonectris borealis
- Caretta caretta
- Globicephala macrorhynchus
Scientific survey records skew toward sampled taxa (molluscs, corals) and do not reflect what you are guaranteed to see on a dive.
Source: OBIS (obis.org), aggregated Darwin Core occurrence records.
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