Mandy Haggith author of The Amber Seeker tells of recreating her protaganist’s voyage

The Amber Seeker is the second of a trilogy of historical novels set around 320BC, and it was mostly written at sea. It is inspired by a Mediterranean explorer, Pytheas of Massalia (now Marseilles, back then a Greek colony), who probably set foot in Assynt, where I live, on the northwest coast of Scotland, during an amazing voyage that included circumnavigating Britain, venturing as far north as Iceland and across the North Sea to the Baltic.

About a decade ago, I was working for an archaeological dig that was excavating a broch – a tall Iron Age building shaped like a cooling tower – which may well have been standing when Pytheas sailed in. And as I read Barry Cunliffe’s brilliant The Extraordinary Voyage of Pytheas the Greek I began to imagine the people that Pytheas would have encountered here. What sort of culture clash, I wondered, would have existed between a Greek scientist and his Celtic hosts? The seed of a novel was sown.

Creating a historical novel involves two phases of research. First, there’s the preparatory work of reading widely and learning enough to be able to conjure people up into a plausible historical setting – how and where they lived, how they moved, what their social structures and beliefs might have been and what events, if any are recorded, may have influenced them.

The second phase of research comes after a first draft has been written, when every single object in the book, and any spoken words, need to be checked for plausibility. This fact-checking work can be arduous and throw up surprises – like the discovery that there’s no evidence of distilling in the Iron Age, so all those scenes with whisky drinking in them had to go back to the drawing board.

During the course of writing the Stone Stories trilogy, I was immensely lucky to be employed by the archaeological team excavating Clachtoll Broch, who shared their insights and prevented me from making too many blunders in the books.

Pytheas was also a writer, but all copies of the book he wrote about his voyage, On the Ocean, seem to have been lost. All we have are fragments from Greek and Roman geographers and historians who quoted Pytheas: some refer to him with admiration and respect for his scientific rigour and fascinating discoveries; others deride him as a fantasist. It seems that many of his adventures were, literally, incredible.

Pytheas’ accounts of his ocean voyages were so outrageous and new to his Mediterranean readers that many took him to be making them up. He was mocked for his tales of great creatures rising out of the sea spouting fumes; islands where the land flows, smoking and burning, into the water; a place where the ocean becomes slushy and semi-frozen; not to mention locations with tidal ranges of many metres.

To us, these details point not to a fabulist but to someone undertaking an extraordinary voyage for his time – daunting even to a modern sailor – up beyond the tidal islands of Britain to volcanic Iceland and the southern edge of the polar ice pack, encountering great whales along the way. I can vouch for the humbling strangeness of the blow of a bowhead whale among ice floes. I just hope the awe and thrill he experienced compensated for the lack of credulity of his readers.

To write about Pytheas I needed to understand better where he travelled. I began with a trip on an ice-breaker up into the Arctic, including time spent in the vast Greenland pack ice and a couple of weeks sailing around Svalbard. There, I sat on a beach with a herd of walrus, which really helped me to imagine what was involved in the work of the hunter Manigan, who is the Walrus Mutterer of the first volume of the trilogy.

It also enabled me to make an educated guess about where walrus would have lived on the Scottish islands. After a week exploring Orkney I picked Sanday as the ideal walrus habitat, so when a walrus actually turned up there last year I felt that I’d been channelling my ‘inner walrus’ pretty well.

And when that walrus headed down into the Minch for the week of my book launch – the first time a walrus had been seen there for more than 50 years – I took it as a strong endorsement from the natural world.

The Svalbard sailing trip got me hooked on sailing, so I set about qualifying as a skipper, bought a boat and discovered that it is a kind of time machine. The sea appears to be in perpetual change, but in many ways it is exactly the same as it has always been.

Although there is nylon, steel and aluminium onboard, the process of sailing is basically just as it would have been in Pytheas’ day: the winds are still Iron Age winds; the waves and the tides are as reliable or ruthless then as now; the landscape, once you’re a mile off shore and the buildings mere dots, could be from anytime.

There’s the same need for constant vigilance, frustration in a calm, danger from a lea-shore in a storm, relief when you make a safe harbour with the wind and sea rising behind you. Out on the ocean, 20th-century concerns sink away and the Iron Age looms into the present.

So I found the boat to be a perfect writing venue. As I scribbled with my fountain pen in my notebook, I imagined Pytheas scratching observations for his book on vellum or parchment with a quill dipped in oak gall ink. Anchorages are usually devoid of mobile phone signals or other distractions, so I spent many happy hours swinging at anchor, allowing the story to ripple out onto the page, the boat populated with a crew of fictional characters.

Out at sea, I have found an ease in sliding between past and present. Then and now are easily accommodated in the vastness of the ocean.

Mandy Haggith’s The Amber Seeker is the second novel in her Stone Stories trilogy, which takes us back to prehistoric times for an epic saga ranging from the sub-Arctic to the Mediterranean. It is out now (Saraband, £8.99). The first novel in the series, The Walrus Mutterer, was longlisted for the Highland Book Prize.