On the opposite side of the Lizard to Porthkerris, Mullion cove is exposed to the prevailing south-westerly wind and sea.On the opposite side of the Lizard to Porthkerris, Mullion cove is exposed to the prevailing south-westerly wind and sea.
At sea there are many sheltered and shallow dive sites round Mullion island. The Dive Cornwall guide book lists three separate cannon sites round the island, but I have never seen a cannon when diving here.
From my point of view the nicest boat dive is a little further south tight in against the cliffs at Pedrannack head. Just as you round the head from the Mullion direction there is a big rock breaking about 15 to 20 metres from the cliff.
In the gully between this rock and the cliff and slightly back towards Mullion are the remains of the 1,500 ton steamship Denise which ran aground in fog in1918. The area of wreckage is small and not much remains, the largest part being the broken boilers in a pebble filled bowl at 15 metres.
Once above the pebble scoured fringes close to the seabed, the vertical rocks are covered in small jewel anemones and occasional clumps of dead men’s fingers. Outside the main rock the reef continues as a series of gently shelving ledges to a depth of 20 metres or so. All nice easy diving with a good spread of marine life.
The shore dive here is very shallow, so absolutely flat calm surface conditions are needed to make it worthwhile.
Outside the harbour entrance follow the wall round to the west and descend straight away. Depending on the state of the tide, it may only be a couple of metres deep, but there are some nice cracks on the outside of the wall and anemones at the base and amongst the rocks.
Just south of the wall are a few large rocks designed to make life difficult for boats at low tide. Boats leaving the harbour will cut tight in along the channel between the end of the wall and these rocks.
Further out, the join between rocks and sand winds its way westwards, with detached islands of rock on the coarse sand identifiable only by the kelp which covers them. Boring from a distance, but there is always the chance of seeing something interesting while foraging under the kelp.
In calm surface conditions the heavy sand settles out quickly, so visibility is usually quite good. There is hardly any point swimming for depth. Just potter out and be content with a very shallow dive and lots of sunlight.
On the other hand, if you need depth for a training exercise, dive as close to high tide as possible and head out south-west across the sand. But pay attention, there is always the chance of meeting a stray spider crab making its way between islands of rocks and kelp. You may also find something good hiding in the sand such as a flatfish or a burrowed in crab.