An estimated 5m (16ft) thresher shark surprised sightseers when it leapt out of the water in front of them.
It happened while they were on a one hour trip to look for dolphins off New Quay, Ceredigion.
Guide and photographer Joshua Pedley said it was a shock when the “huge animal jumped up out of the water”.
A thresher sighting is considered uncommon in Cardigan Bay, with another sighting last year.
“I couldn’t believe it,” Joshua told BBC Radio Wales Breakfast.
“I quickly put my camera up and zoomed in to where it leapt from and leapt again another two times.”
Thresher sharks get their name from their thresher-like tails, which can be as long as their total body length.
They are active predators who use their tails as weapons to stun their prey.
They are often found along the continental shelves of North America and Asia.