
Posidonia Dive
SSI Diamond Instructor Training Center at Port Balis marina, 35 km north of Barcelona, running 24 boat dive sites on the Maresme coast year-round.
Lightly-visited rock at 23-35m off Port Balis, an advanced-only boat dive with reliable rock fauna and an autumn barracuda chance.
Last updated May 2026
The boat anchors above the rock in open water with no fixed mooring buoy, and the descent runs down the anchor line straight into the working range at 23 metres. From there the dive is about reading the rock. The structure sits in the 23 to 35 metre band, and the day's interest concentrates in the crevices and overhangs of the porous Mediterranean rock. A torch earns its place here because the site's value is what lives inside the cracks: morays peering out, lobster tucked in cavities, conger in the larger overhangs, scorpionfish pressed against the rock in summer. The water column above the structure holds the day's pelagic chance, and that chance is real but seasonal. October and November concentrate the barracuda action, with schools working over the top of the rock; amberjack pop up opportunistically, often late in the dive when nothing else is happening. The dive runs roughly 45 to 60 minutes on a 15-litre Nitrox 32% cylinder, with the typical loop tracing the rock face and returning to the anchor line for a conventional safety stop or an SMB ascent if the boat has drifted.
El Templo is the quieter, advanced-only option in the Port Balis rotation. Where Canons and La Virgen offer a shallow flank that absorbs the Open Water and beginner-mixed groups, El Templo has no shallow zone to fall back on, which both narrows its market and keeps the traffic down. The site sees noticeably less traffic than its more popular cluster siblings, and that is its character: a working advanced dive without the headline status, reliable for what it does (rock fauna, depth practice, the autumn pelagic chance) without pretending to be more. It earns its slot for the Deep specialty cohort and regulars rotating through the cluster's depth-cert options.
Bring a torch and an SMB. The whole interest of the dive is inside the cracks, and the boat anchors without a fixed mooring, so the safety stop often runs off-line on an SMB while the boat repositions. Calibrate the suit to bottom temperature, not surface: summer bottom is 15 to 18 degrees at 25-plus metres, so 5mm with hood is the right call from June through September. Winter wants a drysuit or 7mm semi-dry with hood and gloves. Nitrox is recommended on the depth profile and Posidonia Dive fills on-site. Visibility risk to plan for is the winter rierades runoff after heavy rain, which can drop the working range below useful in a single weather window. Garbi (SW) wind days raise surface chop and seasickness on the transit; pre-dose any motion-sickness medication before leaving port, not on the boat. Arrive about 45 minutes before scheduled departure for the standard pre-dive prep window at the centre.
What makes this dive site stand out.
Working range 23-35m with no shallow flank; rated valid for advanced divers only
A quieter slot in the Posidonia rotation than La Virgen or El Santuari nearby
Morays, lobster, conger and scorpionfish in the cracks; a torch earns its place
Pelagic action concentrates around October and November; not guaranteed
41.5376°N, 2.5361°E
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SSI Diamond Instructor Training Center at Port Balis marina, 35 km north of Barcelona, running 24 boat dive sites on the Maresme coast year-round.

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Depth-fixed at 23-35m. Profile is straightforward but the bottom time budget is tight on air; Nitrox is the standard call.
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