Shoals of basking sharks – up to 500 strong – have been reported off the West Country, and their other favourite swimming grounds are the Channel Islands, the Isle of Man, Scotland, Northern Ireland and Wales.

Some of these creatures are up to 8m long and yachtsmen and other water users have helped compile the report which is based on 15 years worth of data.

They arrive off our coasts in April and start to fade away after June. Basking sharks are completely harmless – unless they happen to breach over the top of your boat.