The first thing that the local Gibraltarian divers will tell you is that most of the diving is not the Mediterranean; diving from Gibraltar is mainly in the Atlantic. Wreck diving is centred on the three harbour breakwaters to Gibraltar harbour, or "moles".
The classic wreck on the detached mole is the SS Excellent, and it certainly lives up to its name. The Excellent was a 1600 ton steel hulled schooner with additional propulsion from a steam engine and a huge scimitar bladed propeller. She sank against the wall after a series of collisions in 1888.
Swimming out along the seabed, the hull of the Excellent looms above me, we have hit the wreck where it is broken open at the engine room. Turning right into the arch formed by the upturned hull I enter the hull. I can just make out a dim glow ahead of me marking the exit at the stern.
At the stern we wriggle out of the wreck and head for the bows along the side of the wreck. Plates are arrayed with bright red and yellow gorgonians. Eventually reaching the bows I quietly admire hanging soft corals and tease inquisitive blennies with my fingers before we head back towards the breakwater.
Yet more blennies, carpets of anemones, assorted wrasse and the unusual flying gurnard make their home on the slope and the wall. Examining the small life I start to pick out nudibranchs of all shapes and colours. And all this on just one wreck dive.
On the South Mole lies the wreck of the SS Roslyn, a 3,500-ton steamship that sank in 1916. The Roslyn is a more modern ship than the Excellent, following a classic cargo ship design with holds forward and aft of the remains of a central superstructure and engine room.
Whilst most of the wreck has collapsed in to be just a few metres thick, the bows and stern are reasonably intact, jutting upwards to form a hollow oblique pyramid of plates and girders.
Small rainbow wrasse are pecking away everywhere, even at my fingers if I hold them still for too long. Finning gently towards the stern I dip in and out of holes in the wreckage searching for conger eels and other hole dwelling creatures. A curious cuckoo wrasse follows, meandering in and out of my path.
The 428 was a cable barge used in the naval dockyard. Reaching the end of its working life, in 1990 it was scuttled in 17 metres of water in Camp Bay. Although cleaned up, this wreck was by no means sanitised for divers. When I first dived it in 1990 there was still toilet paper hanging from the holder in the head and an octopus had set up home in the bowl!
Several years on the 428 looks more like a wreck than a ship that just happens to be underwater. Muscles and tunicates grow on exposed surfaces of the hull. Below decks fine silt makes wreck penetration a more serious issue. A massive engine, way out of proportion to the barge's size, provides evidence of the vessels former role.