Paul Semmens, who has surveyed marine life for the Cornwall Wildlife Trust for over 20 years, was aboard the Scillonian III.
The ferry was on a return leg from St Mary’s in the Isles of Scilly to Penzance, with Semmens recording any sightings of marine mammals and sharks.
He knew something might be up when a large flock of gannets was seen ahead, diving to feed on a clearly sizeable school of fish.
In such situations, dolphins are often to be found feeding on the fish too. As the ship approached, common dolphins could be seen manoeuvring in the churning waters.
“These dolphins started to leap out of the water as they came towards us to ride our bow wave,” said Semmens.
“Over the next few minutes, group after group of dolphins came towards the ship, swerving in under our bow and then playing in our wake.
“Passengers rushed to the railings to experience a wonderful wildlife spectacle. I estimated that there were at least 70 common dolphins including some young ones.
“To round off an amazing day, the local group of about ten bottlenose dolphins greeted us on our return to Penzance harbour.”
With Semmens’ help the Cornwall Wildlife Trust, working with the Isles of Scilly Wildlife Trust, runs a Saturday wildlife-watching trip on the Penzance-to-St Mary’s route every month from May to October.
Related links
Cornwall Wildlife Trust
Isles of Scilly Wildlife Trust