"How exactly," frowns the six-year-old, "can we learn about Aberdeen's maritime history without going on a boat, when maritime means everything to do with the sea?"
His big brother is impressed. "Did you learn that watching Octonauts?" he asks, admiringly.
CBeebies telly programmes about undersea creatures aside, we discover that, in fact, it is entirely possible to immerse yourself in Aberdeenshire's rich maritime past without leaving land.
From lighthouse keepers to herring gutters, the oil and gas industry to treasure trails, the area is overflowing with fascinating places.
The city of Aberdeen is our base, with plenty of family-friendly accommodation options, including fine hotels like Ferryhill House with its fantastic food and impressive play area, and stylish apartments such as Westend on leafy Beaconsfield Mews.
Our starting point is the Aberdeen Maritime Museum, a massive multi-floor building on historic Shiprow overlooking the harbour. The nine metre-high Murchison oil platform model, which reaches right up the middle of the building from the entrance foyer, captures our attention from the moment we walk in, and for the next few hours we are entranced by fast sailing ships, giant lighthouse lenses and fascinating stories of drilling for oil and gas.
Back in the sunshine, there is much to explore. Take a walk around the pretty fishing village of Footdee (pronounced Fittie) to learn its secrets and find Fittie Darling's hidden treasure, or head for Stonehaven and Dunnottar Castle, a spectacular ruin on top of a breathtakingly scary cliff (we lost count at 171 steps, so it's not for the faint-hearted - but well worth it).
"This is a proper Famous Five castle," agree the boys, approvingly, dodging in and out of dark chambers, thrilled by tales of its daring and dark past.
It was at Dunnottar that a small garrison held out against the might of Cromwell's army for eight months and saved the Scottish Crown Jewels, the 'Honours of Scotland', from destruction in 1651. A more gentle walk takes you along Stonehaven harbour, with stops for lunch at the Ship Inn, and then Aunty Betty's for ice cream.
Our last stop is Fraserburgh, a picturesque town around 40 miles north of Aberdeen and, fact fans, the largest shellfish port in Europe
There we head for the Museum of Scottish Lighthouses at Kinnaird Head, where, incidentally, the cafe is a revelation, and not just because of its delicious off-the-wall traybakes (peanut mallow, sweetie shop bar, Turkish delight...)
The views of sky and sea seem endless and there is a real danger we may never leave our corner spot, perched high above the waves. On the guided tour, we learn that the strongest gust of sea level wind in the British Isles (142mph) was recorded here, and that being a lighthouse keeper was extremely hard work.
"How did they clean the windows?" wonders Archie, 10. "It must have been exhausting carrying the cans of paraffin up the stairs all the time. I don't think I would have liked being a lighthousekeeper."
Manager Gary Campbell says the lure of the lighthouse is strong.
"Lighthouses fascinate people, probably because we are an island nation," he says. "We are drawn to the sea and the romance of the past." He smiles: "I was a PE teacher in Jordanhill in Glasgow and then I ended up here, because I liked lighthouses. It's a fascinating place to work."
The museum is fantastic, but its less well-known neighbour, the Fraserburgh Heritage Centre, captivates our boys for hours. They learn how to land a catch, spell their names with maritime signal flags and are glued to a 1947 black and white film about net-makers and herring gutters.
"That looks like a horrible job," says Harry, 6, aghast. (They are fast compiling a list of careers of which they plan to steer well clear.) The building was originally a herring barrel store, and it became a museum in 1998, run by volunteers from Fraserburgh Heritage Society.
They had been collating and researching the area's heritage for many years, holding exhibitions in church halls and at galas and fetes. Now there are around 150 members, from local people of all ages to ex-Brochers (Fraserburgh is known as the Broch) living all over the world.
Inside, the herring packers area, harbourmaster's office, cooperage and boatbuilders' yard are reconstructed to show what it was like to work down at the harbour in the 1900s.
We learn that the first lifeboat was established in Fraserburgh, that Guglielmo Marconi conducted Scotland's earliest radio experiments here, and that the town's famous sons and daughters include Polar Medal winner Dr Stewart Slessor, who has a mountain in Antarctica named after him, and Thomas Blake Glover, a merchant who brought isolated Japan into the 20th century, building the country's first railway, and industrial mines.
CURATOR Chris Reid is fiercely protective and proud of her museum. "The big bosses from the Tourist Board came to visit recently and told us we were an 'exemplar' of a community-run museum in the whole of the country," she beams. "I think they were surprised - perhaps they thought we'd be all hemp and home spun.
"We lose out to the Lighthouse Museum - people come to see it and then pop in to us, not realising we are separate and they complain when they have to pay to get in. But once they come in, they love it."
We all loved it too, and start our journey for home, still boat-less, but with heads and hearts filled with stories of the sea.