Illas Cíes & Ría de Vigo

Diving here is organised around the national park rather than around a site list. Centres in Vigo and the towns around the ría hold the diving authorisation, and trips run as day-boats to whichever side of the islands the swell allows: the ocean-facing west on a settled morning, the sheltered eastern coves when it is not. Crossings are short and surface intervals happen aboard, but plans tend to be confirmed the evening before, because both the forecast and park access can move them.

The water is doing something different from the rest of Iberia. Northerly winds drive a summer upwelling that pulls cold, plankton-heavy water into the rías, which is what makes the place green and productive and why clarity swings so hard from week to week: a bloom can shut it down and a settled spell can open it right up. The rock underneath is granite, rounded boulders stacked into caves and crawl-spaces with vertical faces on the exposed side, and the algae cover shifts in character as you drop away from the surface.

Kit decides how much of the day you get. A hood, gloves and a drysuit or heavy semi-dry are the difference between one dive and three in water that upwelling can push into the low teens even in August. Dives are planned around shelter and the state of the tide rather than a fixed route, since the outer faces move water. In exchange you get a temperate Atlantic system that divers arriving from warmer coasts will not have seen before. June to September is the practical window, May and early October can still work, and nothing runs mid-winter.