Seabirds fly below the train as it crosses the Firth of Forth with late afternoon light sparking the water. A kestrel hovers over hay meadows near Kirkcaldy. The lumpy Lomond Hills are sun-misted and the woods are touched with autumn gold. The final stretch of the seven-hour train journey from London to Aberdeen runs along the rocky Scottish shore past forts and firths. (York-Aberdeen costs from £32.30 one way, London from £68.80, lner.co.uk).

Looking back, near Stonehaven station, I can see Dunnottar Castle. The walk from Stonehaven along the cliffs to this castle on its promontory in the North Sea is one of many exceptional car-free days out from Aberdeen. It’s a city I keep coming back to. I first arrived expecting oil rigs, grey buildings, and bad weather – and I found art galleries, wooded lochs, 91 miles of coast, and surprisingly mild weather in one of the UK’s sunniest cities. Aberdeenshire also has good, reliable public transport. I’m spending a week exploring by bus, from the county’s south-west corner in the Cairngorms to Scotland’s first mainland lighthouse on Aberdeenshire’s north-easterly tip. The scenic journeys I take are cheaper with a countywide Bluebird Explorer 7-Day MegaRider (£51.20/£38.40 full price/student).

Just like the blue/green perception test that went viral, your view of Aberdeen as a grey/silver city depends on the conditions. As I arrive, evening sun glints off flecks of mica in the granite walls and the city basks in an early autumn heatwave. I’m staying at the Brewdog Kennels – hip apartments near the train and bus stations that come with a free drink, guitar and record player, and beer fridge in the shower (suites from £115, room only).

Next morning, harbour seals are floating just off the coast as I walk along the promontory at Greyhope Bay. Strolling round the headland, under 200-year-old Girdle Ness lighthouse, I can hear squeaking oystercatchers and mournful curlews. The breakwaters bristle with coastal birds and clifftop gorse bushes are busy with linnets and goldfinches. The glass-walled cafe of the new Greyhope centre looks out across an ever-changing seascape, with a high chance of spotting bottlenose dolphins. Greyhope is a community project that has taken a decade to realise. Marine scientist Fiona McIntyre was working in a nearby lab when she came up with the idea of a cafe to help people connect with wildlife. Greyhope is off-grid, using solar power and treated rainwater and with plans to expand sustainably. The number 12 bus runs frequently from central Aberdeen to St Fittick’s Road nearby.

I spend the next couple of days exploring the Deeside Way. It’s a wooded long-distance route for walkers and cyclists that stretches west for 41 miles from Aberdeen. It mostly follows a disused railway with regular buses 201 and 202 running parallel. The trip is enjoyably full of Scottish scenery and food. As I’m sitting on a bench beside a stream near Drumoak to eat a Tunnock’s caramel bar, a spotted flycatcher sings in the trees and yellow birch leaves land on my shoulders. Later, there’s cullen skink (leek and smoked haddock soup) for lunch at Milton of Crathes before I strip off boots and socks to paddle in the chilly river.

At Banchory Lodge Hotel (doubles from £125 B&B) that night the menu is packed with bream, trout and local tatties. The view from the hotel’s elegant tree-lined lawns after dinner, with fish jumping from the Dee, is worth every blister. Banchory Lodge, 20 miles west of central Aberdeen, is an 18th-century mansion facing over the river to the Bridge of Feugh, where salmon leap up the waterfall in spring and autumn. There’s a bus stop five minutes away – ignore Google maps and take the most direct route down from Arbeadie House. Half an hour further by bus, the village green in Aboyne, bordered by cheerful corn marigolds, looks as neat as a hoovered carpet and the letter box is crowned with crocheted characters from Alice’s Adventures in Wonderland. A toy train runs on a high shelf around the edge of the bar in the old Boat Inn, where you could eat haggis Benedict for breakfast (doubles from £133, B&B).

Next morning, I walk through the Muir of Dinnet, an area of purple heather, bronze bracken, peaceful lochs and waterfalls. It’s the kind of place that it’s hard to believe you can reach without a car, but a wooded six-mile circular walk round Loch Kinord starts from the bus stop in Dinnet. I walk through a mossy ravine to reach a red granite cauldron, hollowed out by glacial meltwater. There’s a prehistoric crannog (artificial island) in the loch and a Pictish cross stone slab on the shore, the felsite carved 1,200 years ago into an intricate tracery of spirals.

There are also Pictish symbols on a new mural back in Aberdeen next day, part of the city’s annual NuArt Festival. A huge face emerges from a craggy Scottish landscape, an aerosol work by Yorkshire muralist Cbloxx (AKA Jay Gilleard). Aberdeen Inspired has made an interactive map where you can browse works from NuArt’s seven-year history and generate a personalised art walk.

Towering over the harbour, a 40-metre painting by the Frankfurt-born artist Hera (Jasmin Siddiqui) shows a girl holding a baby unicorn. Improbably, unicorns are the national animal of Scotland and also feature in an exhibition of prints on show at the light and spacious Aberdeen Art Gallery (until 5 January 2025, free). The exhibition is curated by Nuno Sacramento, director of Peacock, an inspiring open-access print-making workshop celebrating its 50th anniversary. The first poster for the Sex Pistols was printed by Jamie Reid at Peacock in 1975. Among the workshop’s colourful spaces for lithography, screen-printing, etching, and woodcuts is a 19th-century printing machine still in daily use.

In the afternoon, I stroll through Old Aberdeen, over the epic Brig o’Balgownie and along the river to Donmouth nature reserve, where plovers and sandpipers are running over the beach. Later, bus X67 carries me north to Fraserburgh for a last night on the Aberdeenshire coast.

Door to the Shore is a glamping cabin, facing north out to sea, an ideal spot for whale-watching and catching the northern lights (£120/night). There are gulls, guillemots and cormorants on the rocks just metres away beyond a seaweedy slipway. From nearby Kinnaird Head, the automated lighthouse flashes regularly.

Next day, walking past the harbour, glazed eyes stare out from big dockside boxes. Fraserburgh lands more than 14m tonnes of fish each year. The Captain’s Table restaurant, two minutes’ walk down the road is a fishing family-run restaurant that serves local seafood. Manager Sam can tell me the name of the skipper and the boat that caught the fresh langoustines I’m eating. Today’s menu features squid, scallops and rock turbot.

Back in Aberdeen, there’s just time for a farewell cocktail in SugarBird Wines, overlooking the Union Terrace Gardens, before I head for the railway station. These terraced Victorian gardens reopened a couple of years ago after a £28m refurb. Autumn flowers glow in the fading light under reddening maples and hornbeams.

Running overnight from Scotland to London, the hi-tech Caledonian Sleeper, revamped in 2019, feels more Starship Enterprise than Orient Express (seats from £50, bunks from £190, en suite from £250). There’s a pleasingly-reasonable dining car for cabin passengers, where you can order a Brewdog beer and bowl of Thai curry for £15. Tomorrow morning, I’ll eat blueberry pancakes and watch red kites circling over the Chilterns. Tonight, the last thing I see before falling into a deep, rocking sleep is a gleam of moonlight on the Firth of Tay as the train crosses over the water.

This trip was provided with help from Visit Aberdeenshire; transport by Caledonian Sleeper