However there is no need to fear - for this is one of the year’s first sightings of a harmless basking shark cruising off the British south coast.
Every year these graceful sharks return to the seas off the Cornish coast as the seas gradually become warmer.
The basking shark glides through the water as thrilled tourists look on
Passengers on a ''sea safari'' trip spotted a total of four sharks and took these incredible pictures.
The largest of the sharks measured a staggering 16ft in length.
This gentle giant of the sea will have been coming to surface to feed on plankton – much to the delight of the onlooking tourists.
The sharks live on plankton that occurs around the coast as the water warms in the summertime and they venture towards the shore to feed.
The sightings were made only 300m from the shore at Portholland, a small village on the South coast of Cornwall.
Basking sharks can be anything up to 10 metres in length and feed on plankton
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