Els Biotops

The anchor line runs straight down to about 32 metres, onto sand the colour of nothing in particular. Then the blocks appear. More than seventy hollow concrete towers, each roughly five metres tall, stand in rows on the flat seabed, separated by open lanes. Three decades underwater have turned them into precoralligenous outcrops thick with rock fauna. Moray eels sit in the crevices. Fan worms open across the older concrete, and scorpionfish hold still on the surfaces. The route weaves between the blocks and back across the rock toward the coast. It is short, because the depth is real. There is no current and no overhead to manage. The whole demand is staying disciplined about gas and time at 30 metres.

This reef was engineered, not formed. Most diving off Lloret and Tossa runs over natural rocky ridges and pinnacles. Els Biotops is a deliberate structure, sunk in 1994 to defend the seabed, and the dive is a chance to see how that intervention played out. The blocks now do exactly what the project intended: they hold the rock-fauna community the bare sand never could. Dentex and gilt-head bream patrol the lanes. Groupers turn up among the shelter, occasional and wary on this coast. Few Costa Brava dive points are a conservation artefact you can swim through.

In the summer of 1994, more than seventy hollow concrete blocks were lowered onto the sand off Fenals. Each stands about five metres tall. Their job was twofold. The blocks obstruct trawl nets dragged near the coast, and by doing so they shelter the Posidonia oceanica meadow that bottom-trawling destroys. Two independent Lloret operators record the same founding facts: the 1994 sinking, the five-metre blocks, and the anti-trawling and posidonia-protection purpose. The exact commissioning body and the precise block count beyond "more than seventy" were never published.

Boat only, from Lloret. This is a deep dive on a simple layout, so the planning is about depth, not navigation. Carry a computer, dive a conservative profile, and build in a safety stop. Nitrox extends your bottom time and adds margin at 30 metres. A 7 mm wetsuit with a hood is the summer minimum, since the bottom sits well below the warm surface layer; in the shoulder and winter months a drysuit is the comfortable choice. The marine life is best from late spring through autumn.