"That's an awkward question," he laughs when I ask why. "It's exactly what it says."
Likely a woman from New Zealand he wishes I hadn't asked about. The answer is a shrug, but the boat itself is anything but plain.
I boarded Kiwi Girl on a grey morning in August, decked out with sun cream and raincoats.
A dozen of us filed on: Parents with children down from Dublin, waterproofs zipped up against the mist; a dry-robed couple; and beside me, the filmmaker Joshua Nueva, whose lens has made him one of Ireland's most prolific chroniclers of sea life.
The engine shuddered into life and we pulled out of Mullaghmore Harbour, the headland falling behind as Donegal Bay opened.
We did not have to wait long. Dolphins broke the surface off the bow in slick black arcs, quick as commas. A minke whale erupted from the waves.
The children screamed and pointed, already scribbling into their own mental field notes. One girl whispered: "They're playing chasing."
I remember her as the kind of child who might grow into a marine biologist, or simply someone who cannot stay away from the sea.
Declan's life has been lived on water. He started young, teaching diving with no money, no gear, "no nothing", he says: "We needed to buy a boat. What we could afford was small, just enough to get us out a wee bit. Then bigger boats, and once the boats got too big... to start paying for them, the diving needed to be subsidised, and fishing started subsidising that."
Eventually, the fishing grew and the diving shrank.
"I wasn't diving at all," he admits. "I spent most of my time fishing."
But fishing now is less about the catch than the record, he explains: "We'd catch, tag, measure, record. We do shark tagging through Sea Fisheries Protection. We do the tuna Chart work through Inland Fisheries."
On board, it becomes clear: The Kiwi Girl is a moving ledger of the Atlantic. Declan knows the whales the way neighbours are known, by habits and scars.
"Some of the whales have nicknames. We were with 89 last night, which is Hook," he said. "He doesn't fluke, so we don't know quite what's going on there."
Fluking is when whales pop their tails above the water to help them dive down. They call him Hook because it looks like he has a hook.
A whale's "tail has a unique pattern, like a fingerprint, but Hook doesn't show his tail. Maybe he had an accident somewhere along the way. Got hit with a ship or whatever".
And then there is whale 24 -- Declan's favourite, the whale he has "spent the most time with".
He recalls: "I thought we had a bond. He never showed up last year, and I was really disappointed. Then one day, there he was ahead of me. I got close enough to go; 'I know who that is'. It's very unique. And it was wow, 24 is back."
But the sea is shifting beneath these bonds.
"I think there's been a bit of a shift northwards with wildlife," Declan warns. "If we lose the food source and the whales move on another 200 miles... It's all over. They'll be so close to Norway, and they won't bother coming down."
The culprit is overfishing: "Excessive commercials. We're going to lose it. It's inevitable. When you're taking away a massive food source from so many animals to grind it down, crush it, process it to feed farm salmon, I don't get it at all."
Ireland's south coast once carried the fame of whale watching. West Cork was the "big spot". If the whales move further north, Donegal and Sligo may be next to lose them.
The míol mór, or "great beast", has haunted Irish waters and imagination for centuries. Annals from the 13th century record whale strandings in Kerry.
Legends tell of St Brendan mistaking a whale's back for an island. By the 18th century, observers wrote that whales "abounded" off Sligo each spring.
Later came whaling stations in Donegal and Mayo, their catches so excessive that by 1925, the industry collapsed under its own greed.
Ireland's redemption began in 1937, with the Whale Fisheries Act banning whaling, and culminated in 1991 when the government declared all Irish waters a whale and dolphin sanctuary -- the first such declaration in Europe.
It was a symbolic act, but not an empty one. It forced a reimagining of whales as neighbours, not resources.
That reimagining was amplified at the European level. Under the EU Habitats Directive 1992, all cetaceans are strictly protected.
The Shannon Estuary is a special area of conservation for its resident bottlenose dolphins; Roaringwater Bay, Dalkey, and Rockabill are set aside for harbour porpoise.
Regulations require acoustic "pingers" on nets to keep dolphins away, and prohibit deliberate disturbance of whales. Europe speaks as one voice at the International Whaling Commission, an unambiguous anti-whaling bloc.
The law is there, but the sea remains precarious. Plastic gathers in stomachs, shipping noise drowns out songs, and climate change is already pulling prey away.
What Declan sees, the slow vanishing of the feast, is borne out by data as much as by instinct.
Recently, Nueva's drone rose above the Kiwi Girl and caught what our eyes could only glimpse: Dolphins in formation, white wake slicing the slate water.
His camera translates awe into pixels, making Mullaghmore's wild Atlantic legible to a world that may never set foot on a boat. He is, in his own way, building a sanctuary in image.
Declan says people come back again and again, some unable to resist the pull of the whales: "People get emotional, really, really emotional. One woman comes every month... she was crying from the boat. She just wants to be here every day. She can't obviously, but she's out now once a week."
The day we went out, we saw only one Minke whale. There were mostly dolphins, as if to remind us that this is not an aquarium but the Atlantic itself, unpredictable and wild.
Yet, no one left disappointed. Declan smiled when asked about expectations: "The biggest mistake is just expecting.
"Chance of seeing an orca? None. Never happened. Then last week we had an orca in the bay. So, you know... anything can happen."
Anything can happen. That is the promise of Kiwi Girl, and the burden too. The whales are still here, for now, and we still have the chance to meet them.
But whether the míol mór remains a neighbour in Sligo Bay -- or becomes once again only a word in old stories -- depends on whether we choose to leave enough on the table for them to return.
The children on the boat, faces lit up at the sight of dolphins, do not think of overfishing. For them, it is immediate: The slick surface broken, the sudden spray, the feeling that another world full of joy is playing just beneath.
They will carry that moment like a miniature bottle tucked into memory, to be opened years from now.
If overfishing drains the sea, if plastic fills the stomachs of giants, if noise drowns their songs, then the next generation will inherit only stories.
Míol mór will slip back into folklore, another creature mistaken for an island, another ghost that once swam here.
Anything can happen: A pod of dolphins in Sligo Bay, an orca where no one expected it, or silence.