Sharks are one of the great joys of British coastal life. Not, of course, the nasty ones, the great whites of Jaws or those other two oceanic ultra-aggressors, the bull and tiger shark, but the outsize yet benign basking shark.

Basking sharks usually appear off British waters from early summer onwards. They should arrive at my local beach, Porthcurno, in west Cornwall, any time now, drawn by the plankton that is borne landwards as the sea warms up.

They are remarkable, beautiful creatures, capable of breaching entirely, but more likely to glide slowly on the surface, cavernous jaw open, passively filtering plankton and small fish from up to 2,000 tonnes of water an hour Their sheer size — the basking shark is the second-largest shark, eclipsed only by the whale shark — has always made me nervous of getting up close and personal with them.

My children are scathing of this cautionary stance. Two summers ago, at nearby Sennen Cove, they were surfing when six or seven basking sharks materialised. I was on the beach and could only watch with mounting apprehension as the sharks grew closer.

My elder son, Harry, waved excitedly at me, while his brother, Elliot, reached out to touch one of the sharks. On the shore afterwards both were ecstatic. “I touched a shark!” said Elliot. “They were pretty cool,” Harry said, his discerning older sibling’s sang-froid belied by his beaming face.

The sharks were back at Porthcurno a few days later. Locals and tourists were captivated as they drifted close to the beach. To the chagrin of the lifeguards, a few people decided to swim out to them. The lifeguards weren’t being killjoys; they simply wanted the sharks to be left in peace to feed.

This proved my salvation. “Come on, Dad, let’s swim out to them!” the boys implored. I agreed that we would venture into the sea, but only if we kept our distance; after all, if a shark’s got to eat, a shark’s got to eat. Ecosystems must be maintained. “You’re a wimp, Dad,” my sons said, as one.

They are right. But however mesmerising basking sharks are, some things about them are best left a mystery. That includes discovering where they go in winter — if anyone knows, please don’t tell me — and finding out if they have sharp teeth.

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