THE BARRACUDA CIRCLE near the surface, at first barely visible through the thick blur of thermocline, then picked out sharp against the sunny sky above as I ascend for a better look.
There aren't all that many of them – a couple of hundred, perhaps – but the swirling shoal is a welcome and unexpected sight here in the Mediterranean, just a short distance off the coast of Benidorm.
The Sierra Helada Natural Park, with its nearly 5000 hectares of protected waters, is clearly doing what it's supposed to do.
I’m describing a circle myself, around Mediana Island, a wedge of scrub-covered rock dwarfed by the towering sandstone cliffs of the Sierra Helada – or Frozen Mountain – so-called because it looks like an iceberg when viewed from the sea at night.
It's windy up top so there's quite a lot of stuff suspended in the water, but visibility is still 10-15m for most of the dive, enough to make out the impressive drop away into the blue of the sheer wall on the ocean-side of the island.
I'm here with Jorge from Diving Stones, a PADI 5* centre conveniently based in Benidorm’s petite harbour. It took us just 15 minutes to get out here in the dive centre's speedy RIB, a beautiful ride east along the sweeping stretch of Levante Beach and the rugged landscape of the Sierra Helada.
It's only early June and the water is still a chilly 18°C at depth. Trade will pick up as the summer advances and the temperatures rise, Jorge tells me, but I can't say I'm sad to have the place to myself.

MEDIANA ISLAND, with that deep wall to explore, was supposed to be the first dive of the day, but the wind prompted a last-minute change of plan.
Overly choppy seas would have made access to the cave system at the foot of the cliff impossible, so Jorge decided that we'd do the caves first, and finish with the island after a surface interval rocking and rolling in the blazing sunshine.
We began with Elephant Cave, dropping into the water beneath the distinctive cliff-face rock formation that gives the cave its name. Ducking between algae-covered boulders, I descended into a small chamber that opened out into a corridor, its walls almost devoid of life.
Around 15m into the rock, the cave opened up above me and I ascended to the surface, my torch catching on langoustine, sea cucumbers and scurrying shrimps as I passed.
Up top the darkness was total, my light casting eerie shadows on the high ceiling and stalactites, my splashing about causing the resident conger eel to hide at the very back of its den.
Having exited Elephant Cave the way I entered and emerged into the brilliant blue of a sunlit sea, I followed an extravagantly abundant wall south towards the entrance of cave number two. Pink flabellina nudibranchs, blooming sun coral and waving tubeworms distracted me as I made for the wide overhang marking the location of Dwarf Cave.
Clouds of black damselfish flitted about in the blue outside the suddenly narrowing passageway, soon forgotten as I twisted my way through the darkness and up to the surface again – to find a small chamber with a garden gnome sitting smugly on a ledge in the rock.

THE BEST PART WAS YET to come, a tiny air-pocket on the way out of the cave flooded with otherworldly blue light from the chamber below.
As I bobbed at the surface, the top of my head just inches from the ceiling, the steady boom of the swell against the cliff face reverberated through the rock like the footsteps of an angry giant.
The next day’s excursions are with Nisos, Benidorm’s other dive centre and the home of technical diving in the area. Located a short drive from the harbour, Nisos has the space for a small shop and changing rooms and showers of its own (as opposed to Diving Stones, where divers must use the facilities in the harbour building).
My heart sinks at the idea of lugging gear about in the hot sun between the dive centre and the RIB, but Jessica and her team ensure that the process is a painless one.
Directly off shore from Benidorm’s old town is Benidorm Island, a spot popular for boat trips and seaside hikes. Its geography makes it diveable whichever way the wind is blowing. With around 10 sites from which to choose, including caves, reefs and walls, and located just a few minutes off the mainland, it’s the heart of the local dive scene.
Our first stop is La Llosa, a site directly south of the island. Polish dive guide Gosia leads me straight down a steep wall, descending to 28m to duck beneath some boulders in search of a small cave bearing a statue of the Virgin Mary.
On the way in I come face to face with the biggest scorpionfish I’ve ever seen, and make sure I don’t disturb it in the limited sandy-bottomed space.
Keen to conserve my air, I shallow up as I follow the wall around, eventually reaching a plateau at 8-10m that resembles nothing more than a rolling hillside, complete with grazing goatfish.
Enormous Swiss cow nudibranchs are my favourite local find, visibility of around 20m making them easy to spot even from far away.
I peer over the edge of the plateau down into the deep, boulder-strewn landscape below and feel a momentary touch of vertigo at the sight.
Dive two with Nisos is at Garbí, a sheltered bay on the Benidorm side of the island that both dive centres sometimes use for open-water training. A glass-bottomed tourist boat passes with a roar as I cross a sandy seabed to reach a gently sloping wall, the continuation under water of the gradient of the island.
Maximum depth here is around 18m but you could do this site shallower if you wanted – the whole area is covered with nooks and crannies attracting damselfish in their thousands, goatfish, bream, solitary dentex, barracuda, little parrotfish and wrasse.
It’s a less dramatic scene than the dives I’ve done so far in Benidorm, but it’s enjoyable nonetheless.
I’ve been warned that octopus are less common here than they used to be – victims of the illegal small-scale spearfishing that goes unreported and unpunished in this supposedly
protected area.
Yet right before the end of the dive I spot one, trying to hide itself away in a hole not quite big enough for the purpose. It’s a cheering sight, and I wish the little chap well as I start my final ascent of the trip.
I came to Benidorm full of preconceptions, imagining barren seas and loutish landlubbers, but I had my prejudices overturned in just a couple of days. Lots of marine life, thrilling cave-diving and plenty of classy topside fun (see fact file for recommendations) – viva España indeed!

FACTFILE
GETTING THERE A range of airlines fly to Alicante (the flight takes 2.5 hours). Hire a car or take a cab or shuttle-bus to Benidorm 45 minutes away.
DIVING Diving Stones, www.divingstones.com. Nisos Benidorm, www.nisosbenidorm.com. A medical certificate is required for diving in Spain.
ACCOMMODATION The Marconfort Essence is a 4* all-suite adults-only hotel (www.marconfort.com)
WHEN TO GO: Year-round.
WHEN NOT DIVING: La Taperia de Aurrera (www.grupoaurrera.com); Belvedere Restaurant, (belvederebenidorm.com); Restaurante Posada del Mar; Restaurante Barranco Playa (www.barranco playa.com); Restaurante La Senoria; Hotel Villa Venecia (www.hotelvillavenecia.com). 4x4 tour of countryside with Marco Polo Expediciones (www.marcopolo-exp.es); wine-tasting at Bodegas Mendoza (www.bodegasmendoza.com).
PRICES: Budget flights to Alicante from £100. A week at the Marconfort Essence costs around 1200 euros for two sharing a suite (September prices). Diving Stones charges 35 euros for a single dive or 250 euros for a 10-dive package. Nisos Benidorm charges 30 euros per dive with free pick-up.
VISITOR INFORMATION: en.visitbenidorm.es