Cornwall water temp and sealife overview

Cornwall has a wonderfully diverse and rich marine environment, an environment that changes throughout the year. We are often asked ‘when is the best time to freedive in Cornwall’, and there really is no right answer, it just depends on what you are looking for.

In the winter the water can be clear but often the storms make inshore water very murky, there is also very little fish life. In the spring, when the storms have died off, the water can be very clear (the clearest all year )… still cold though. In the summer the water is the warmest, with the most fish life and with good visibility.

The basking sharks come in during the spring months, following the plankton bloom that can make the water a bit murky for a few weeks during late May. They will stay about all summer but in fewer numbers.

We also get the spring spider crab migration at the same time, coming in droves to mate in shallow water.

As summer approaches the plankton drops and the water clears up again, but now with more fish than at any other time of the year. Shoals of seabass can be seen darting across the reefs and if you are really lucky Dolphins, shark and Sunfish!

Below is a chart which we have put together to give you an idea what to expect down here, throughout the year.