Birdwatchers on a day trip off the west Wales coast found two killer whales instead.
Orca whales are familiar to millions from the Free Willy films
The 40-strong group were training their telescopes and binoculars out to sea at Fishguard when they spotted a 6ft fin cutting through the water.
There have been reports of the mammals off the coast before but they are still a rare sighting.
Cliff Benson, who was among the party from the mid Pembrokeshire section of the Wildlife Trust South and West Wales, said it "blew your socks off."
Killer whales can grow up to 28 feet long and eat seals, dolphins and other whales.
Mr Benson said: "We did not expect to see anything at first because some jet skis shot by and scared most of the birds away.
"But then somebody saw a big fin and there were about 40 of us all with telescopes and binoculars so that got us looking for things. Suddenly there were several big fins out there.
"The first ones were definitely Risso's dolphins, which are bigger than the usual flipper-type dolphins.
"Then somebody saw an even bigger fin about six foot tall and the white eye patches and white flanks of what everybody recognises from the Free Willy films - an orca or killer whale.
"There were two of them, possibly a male and female.
"They were about a mile odd off the coast. You would not have seen them without telescopes or binoculars, but they are there. It blows your socks off."
As well as killer whales, several species of shark have been recorded in the coastal waters, including the enormous basking shark, according to the Pembrokeshire National Park Authority.
It said pilot whales and sun fish had also made appearances but sightings were relatively rare.