Start with the document we actually have
Atlantis reaches us through a conversation written by Plato, not through an excavation report. In Timaeus, a character called Critias presents a tale passed down through other speakers and attributed to Solon's visit to Egypt. Within that literary frame, Atlantis is a powerful island beyond the Pillars of Heracles, defeated by ancient Athens and later overwhelmed by disaster. The dialogue is evidence that Plato told this story; the chain of speakers inside it is not independent confirmation that its events occurred.
Critias adds an elaborate island economy: canals, agricultural land, harbours, materials and rulers. Those details make useful questions for a writer. They do not turn the dialogue into a surveyed map. Our fictional chapter borrows the problem of a prosperous port in danger, rather than claiming to complete a missing archaeological record.
Sources: plato-timaeus, plato-critias
What a real volcano can and cannot explain
Santorini offers a real example of an island repeatedly reshaped by explosive volcanism. The geological account catalogued by the US Geological Survey describes successive eruptive centres and several caldera-forming episodes, including the late Bronze Age eruption. This establishes that dramatic island destruction belongs to the physical world. It does not establish that Santorini was Atlantis, or that an eruption explains every part of Plato's narrative.
For Marrow Harbour we therefore choose a small invented volcanic island, an entirely invented population and no real coordinates. A damaged quay, contaminated water and an interrupted grain supply are sufficient threats. A continent does not need to disappear for a home to become uninhabitable. This is a storytelling decision, not a geological finding.
Sources: santorini-geology
Build the ordinary systems first
The invented port grows some of its food on upland terraces and imports grain when harvests fail. Households collect rain in covered cisterns. Fishing supplements meals; it does not magically replace every lost crop. Boatbuilders need timber, rope and labour. Storage managers need dry floors and a way to settle disputed claims. These are design constraints: each new luxury must have someone producing, carrying or paying for it.
The chapter's clay tallies, lending customs, evacuation order and characters are invented. Its central dispute concerns whether merchants retain priority over grain that the town now needs to move inland. That choice makes the city political without pretending that its laws have been recovered from the seabed.
What remains open
A historical claim would require a particular site, dated deposits, identifiable objects and a defensible connection between those finds and the claim. We supply none of those for Marrow Harbour. Its evacuation is an imagined alternative to the familiar spectacle of universal destruction. Readers can compare how the story uses evidence; they should not cite its events as evidence about ancient people.