Cardigan Bay, Wales

Winter colours: a corkwing wrasse in breeding colours rests on the sea bed Photos: Paul Kay Cardigan Bay Photo: Shutterstock.com A butterfly blenny shelters under a shell in winter Photo: Paul Kay

Open sea with a fairly flat sea bed may not sound like the ideal dive site, but in Cardigan Bay, you might just be pleasantly surprised. During the winter, it is sometimes possible for calm weather to allow for some RIB diving, and while visibility is unlikely to be stunning, it can be acceptable.

So what’s so interesting about a sand/gravel/cobble sea bed at between 15 and 20m in winter? Well, it’s the fish! Some fish seem to stay where they live for the rest of the year and just hunker down in the cold weather. The area to the east of St Tudwal’s Islands is one of the places where you can find butterfly blennies. In the summer, they can often be spotted in whelk shells where the males guard their eggs. But in the winter, they seem to disappear – that is, until you look carefully. What they actually do is shelter under shells and stay as still as possible in order to conserve energy. If you are careful and observant, they can be spotted – but shouldn’t be disturbed because doing so will make them use up precious energy.

Corkwing wrasse are common enough in summer, but in winter they too conserve energy. These fish simply seem to lie on the sea bed and sleep. As winter progresses into spring, the males become vividly coloured – in breeding condition – and can be spotted quite easily, although again, it’s best not to approach too close or they will make the effort to swim off.

The problem with seeing such creatures and discovering how they behave in winter is, of course, the weather, and often it’s simply not possible to get out to such dive sites. When and if you can, it’s possible to find out how they survive the cold, harsh conditions to be found in British coastal waters. Even today, it is probably still possible to make observations that few others – if anyone – have ever made.

Difficult environments take a great deal of studying and it is intriguing to think that there is a lot of behavioural information that still remains unknown, even on our own doorstep.

To find a local dive centre/boat, go to page 107 of DIVE’s Classified section