A group of intrepid shark hunters has set sail to look for giants of the deep circling the Northern Ireland coast.
Basking Sharks are a rare sight in British waters
They will be spending five days and nights looking for the second largest fish on the planet - the basking shark.
The expedition is an Ulster Wildlife Trust survey on their habits.
Getting close could be a challenge, with only 108 sightings in British waters last year they are nearly as hard a fish to find as Nemo.
However, the skipper of the 39ft cutter Forever Changes, Colin Speedy, said it was a vital task and that they had received two public sightings near Portrush in County Antrim this year.
"You simply can't work out strategies to preserve an animal if you don't know how many there are in the first place, ie you simply don't know if the population is increasing or decreasing," he said.
The yacht carrying conservationists and local volunteers left Bangor in County Down on Saturday.
Basking sharks are enormous creatures - growing up to 12 metres long with some weighing more than five tonnes - but they spend most of their time cruising along feeding on plankton.
Mr Speedy said anyone who sees one should report the sighting to the UWT, but treat the animal with respect.
"They are pretty big and pretty dim, and they're big slow feeding machines and once they're locked into some really dense plankton then they are difficult to disturb, so watch out - don't go too close," he said.
Irish Sea Officer for the Ulster Wildlife Trust Kate Hutchinson said they hoped to carry out a survey every year.
"This is the third year it has happened, this survey, and we are wanting funding to carry it on into the next couple of years," she said.
The yacht is staffed with a mostly volunteer crew, and for a number it is their first time on such an adventure.
One on them, Malachy Campbell, said he was hoping to spot a shark.
"I work for WWF Northern Ireland and we're very interested in marine conservation issues. We work with the wildlife trust on marine issues so I'm hoping to see basking sharks as well," he said.
Hunting them was banned last year, but their fins still fetch thousands of pounds in the Far East, so conservationists know they have not yet won the battle to save these gentle giants.