I have a novel ¼ written and this is not the setting but it's a foreign country in the world.

Concept

North Atlantic island cultures are actually small and limited.

What if there were 7× as many islands, packed closer together? That would mean more trade, more cultural interaction, a stronger power. The sea becomes less of a barrier and more of a highway.

Stats

Real life: Faroes+Hebrides+Shetlands+Orkneys+Iceland have about 1400 islands, of which about 10% are inhabited, about 550,000 population, about 115,000km² area, so 4.8 people per km²

Multiply by seven: 9800 islands of which 980 are inhabited, population of 3.85 million, area of 805,000km² (comparable in size to Turkey), population density remains 4.8/km²

Landscape

Rugged and rocky with cliffs. Formed by volcanoes 50-60 million years ago and then eroded by glaciers and sea to form dramatic landscapes.

The Faroes have five mountains over 800m which are snow-covered a large part of the year. This proves that pretty big mountains can exist in this geography, and for fiction, we can push this up to 1000m.

Freshwater streams and lakes are rare, most islands do not have them. If you go from an island without freshwater to one with freshwater, it's a different kettle of fish, including trout.

Weather

Generally harsh, windy, cloudy, cold. Excellent wind and tidal power if you're talking about 21st-century tech level. Wind-power can also be harnessed centuries earlier, of course.

If you want to write micro-climates (like Summerisle in The Wicker Man) that is very realistic because of the way currents, mountains, and winds interact.

Un-sunny. The capital of the Faroes, Tórshavn, has 840 hours of sunshine per year (lowest of any city in the world). Reykjavík has 1368.

Turf houses

The blackhouse is a traditional house with double wall dry-stone walls packed with earth, roofed with wooden rafters covered with a turf weighted with stones.

Inside is a central hearth for the fire, largely fed by turf rather than wood, though it depends on which island. No chimney: the smoke blackens the thatch and preserves it.

The turf houses shelter livestock as well as men; the body-heat helps warm the place.

Icelandic turf houses (torfbæir) are made of timber with the walls and roof covered in turf. Similar æsthetically to the blackhouse, but using less stone; it depends on whether wood or stone is more available on the particular island. (The Faroe islands are treeless; Iceland was 30% forested when discovered.)

Means of production

Fishing and whaling are obviously the main ones. A "Faroese speciality is tvøst og removed, made from pilot whale meat and blubber"

Fresh and dried fish are both important. The drying shed, known as a hjallur, is a standard feature in many Faroese homes. Seabirds (puffins, auks, etc.) are caught in nets and eaten, and their eggs are harvested from their nests.

Edible crab and oyster, horse mussel and brittle star.

Seals are eaten and feature in the folklore and heraldry. Grey seal and harbour seal.

Land agriculture

It's not all fish: geese, ponies, sheep (and sheepdogs), cattle, duck, and pig are important.

The Shetlands are of course famous for their small strong Shetland Pony. There's a Shetland sheep and a Faroe sheep. There was a boar-like landrace of pig in the Shetlands until 1930. Here's some Faroese geese –

Hardy sheep are basically the best way to turn a yield from marginal rocky land. The islands have heather moors dominated by shrubby heathers (especially calluna vulgaris), with ling, bell-heather, cross-leaved heath, bog myrtle, arctic-alpine plants including alpine pearlwort and mossy cyphal.

Crofting is an agricultural practice in Scottish islands that avoids open-field agriculture and focuses on small (2-5 acre) holdings for vegetables and animal fodder. (Off-topic for worldbuilding: the crofters have applied to the U.N. for indigenous status, so far unsuccessfully. Donald Trump's maternal grandfather was a crofter.)

Sheep + cold means woollen clothes are a key visual signifier of the culture. Look at this beautiful picture of indigenous Greenlandic women: