Mediterranean · Spain
Islas Columbretes
A drowned volcanic crater 50 km offshore, with permit-limited diving
Photo: JavierValencia2005 · CC BY-SA 4.0
The Columbretes are the eroded remains of a volcanic field 50 km off Castellón, protected as a marine reserve since 1990 and visited by a strictly limited number of divers each day. The main island is a drowned crater whose horseshoe rim encloses a natural harbour, and the surrounding rock rises from 40 m in chimneys and arches. With almost no fishing pressure and no coastal runoff, the water is clearer than anywhere on the Spanish mainland and the groupers are unafraid.
About diving in Islas Columbretes
Diving the Columbretes is a committing day rather than an outing. Boats leave the Castellón coast early, the crossing takes about three hours each way, and the day is built around two dives with the surface interval spent moored inside the crater harbour. Everything needed goes with you, since there is no shop, no fill station and no second chance if a piece of kit was left on the mainland. Landing on the islands is tightly restricted.
The rock is volcanic and behaves like it. Diving runs from the reserve's fixed mooring buoys under a strict permit and quota system, on walls and slopes around the outer islets. The landmark chimney of El Carallot rises bare from the seabed south of the group, but it sits inside the integral reserve and is closed to divers. At L'Illa Grossa the dive starts down a buoy line inside the crater, to a sand patch ringed by rock formations at 16 m.
Two things make the diving distinctive: the water and the fish. With no rivers, no coastal runoff and 50 km of open sea between the archipelago and the mainland, visibility is better than anywhere along the Spanish mainland coast, and the reserve's daily permit cap keeps the sites unpressured. Current is usually mild, so it is depth and the crossing, rather than the conditions on the day, that set the difficulty.
It suits divers willing to trade convenience for a reserve left alone since 1990, and anyone more interested in big grouper, clear water and volcanic topography than in a long list of sites. Advanced Open Water divers can dive L'Illa Grossa to 30 m once the permit is arranged. Operators run May to October, and summer places go early.
Best time to dive Islas Columbretes
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Season | Off-season | Off-season | Fair | Good | Good | Prime | Prime | Prime | Prime | Good | Fair | Off-season |
| Sea surface | 15°C59°F | 14°C57°F | 14°C57°F | 16°C61°F | 19°C66°F | 23°C73°F | 26°C79°F | 27°C81°F | 26°C79°F | 23°C73°F | 19°C66°F | 16°C61°F |
| Daytime high | 18°C64°F | 17°C63°F | 18°C64°F | 19°C66°F | 22°C72°F | 26°C79°F | 28°C82°F | 29°C84°F | 28°C82°F | 25°C77°F | 22°C72°F | 18°C64°F |
| Rain | 43 mm1.7 in | 30 mm1.2 in | 63 mm2.5 in | 49 mm1.9 in | 36 mm1.4 in | 29 mm1.1 in | 16 mm0.6 in | 31 mm1.2 in | 69 mm2.7 in | 66 mm2.6 in | 73 mm2.9 in | 42 mm1.7 in |
| Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|
| Off-season | Off-season | Fair | Good | Good | Prime |
| Sea surface | |||||
| 15°C59°F | 14°C57°F | 14°C57°F | 16°C61°F | 19°C66°F | 23°C73°F |
| Daytime high | |||||
| 18°C64°F | 17°C63°F | 18°C64°F | 19°C66°F | 22°C72°F | 26°C79°F |
| Rain | |||||
| 43 mm1.7 in | 30 mm1.2 in | 63 mm2.5 in | 49 mm1.9 in | 36 mm1.4 in | 29 mm1.1 in |
| Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|
| Prime | Prime | Prime | Good | Fair | Off-season |
| Sea surface | |||||
| 26°C79°F | 27°C81°F | 26°C79°F | 23°C73°F | 19°C66°F | 16°C61°F |
| Daytime high | |||||
| 28°C82°F | 29°C84°F | 28°C82°F | 25°C77°F | 22°C72°F | 18°C64°F |
| Rain | |||||
| 16 mm0.6 in | 31 mm1.2 in | 69 mm2.7 in | 66 mm2.6 in | 73 mm2.9 in | 42 mm1.7 in |
2011–2025 averages. Sea surface: NOAA Coral Reef Watch, measured at the surface, so deeper water can run colder. Daytime high and rain: NASA POWER.
Operators run May–Oct; the three-hour crossing is impractical in winter and the reserve issues a capped number of daily permits.
Best months: June, July, August, September
Islas Columbretes water temperature and weather by month
The sea surface runs from 14 °C (57 °F) in February to 27 °C (81 °F) in August. It is 24 °C (75 °F) or warmer from July to September. Most rain falls from September to November, peaking at about 70 mm (2.8 in) in November; July is the driest. Daytime highs reach 29 °C (84 °F) in August and drop to 17 °C (63 °F) in February. The coldest water here is about 14 °C (57 °F), so pack a 7 mm suit with a hood, or a semi-dry.
Dive types & marine life
Groupers are the constant and they hold their ground, which is the reserve's defining sight. Barracuda and reef-fish shoals gather on the chimneys, tuna pass in open water and turtles turn up occasionally through the warm months. Octopus, cuttlefish and nudibranchs reward slow dives on the shallow rims, with June to September the prime window.
- Reef
- Wall
- Cave & cavern
- Seamount
- Groupers
- Barracuda
- Tuna
- Octopus & cuttlefish
- Reef fish swarms
- Nudibranchs
- Sea turtles
Best dive sites in Islas Columbretes
Reef
A buoy descent into the crater, with big groupers and morays
El Carallot
Volcanic chimney off l'Illa Grossa — inside the integral reserve, closed to scuba.
La Ferrera
Outer islet group of the marine reserve; dives run from the fixed mooring buoys.
La Foradada
Pierced outer islet in the reserve's southern group, dived from the fixed moorings.
How to get to Islas Columbretes
Trips leave from the Castellón coast and the crossing runs about three hours each way, so expect a full day afloat. Valencia is the practical airport. Places are capped by reserve permit and arranged by the operator, so book well ahead for summer dates.
Photos from Islas Columbretes
JavierValencia2005 · CC BY-SA 4.0
Dive videos
Columbretes 2022 · CLOTXA Produccions on YouTube
Photo credits
- L'Illa Grossa and volcanic sea stacks of the Columbretes rising from open blue sea by JavierValencia2005, CC BY-SA 4.0, via Openverse
- Natural arch cut through the volcanic rock of a Columbretes islet by JavierValencia2005, CC BY-SA 4.0, via Openverse
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