Imperfect Peaks of Eternal Light and Craters of Eternal Darkness are potentially ways of getting interestingly asymmetrical day/night cycles.

Imagine a planet that has no axial spin, so the stars remain fixed in the sky, never rising nor setting, and no axial tilt. At the northern-most point, there is a humongous crater, whose mountanous rim has a single gigantic chasm in it. As the planet orbits the star, the angle the sun makes with the North Pole changes, and once per year it shines through the gigantic chasm, allowing the inside of the crater to recieve light for a few days.

(Or perhaps there is a small axial tilt, and at the height of summer, the sun pokes above the crater's rim)

This crater contains water, and the archipelago in question.

Quite how the crater walls are so high is suspicious -- I'd suspect some sort of engineering, because the crater walls are going to need to be high enough to be visible from over the horizon (how else do they block the sun?) and that height grows very fast as the angular size of the archipelago grows...

Potentially relevant to your interests: a town in a valley in Norway, which is dark during the middle of the day...

Imperfect Peaks of Eternal Light and Craters of Eternal Darkness are potentially ways of getting interestingly asymmetrical day/night cycles.

Imagine a planet that has no axial spin, so the stars remain fixed in the sky, never rising nor setting, and no axial tilt. At the northern-most point, there is a humongous crater, whose mountaneous rim has a single gigantic chasm in it. As the planet orbits the star, the angle the sun makes with the North Pole changes, and once per year it shines through the gigantic chasm, allowing the inside of the crater to recieve light for a few days.

(Or perhaps there is a small axial tilt, and at the height of summer, the sun pokes above the crater's rim)

This crater contains water, and the archipelago in question.

Quite how the crater walls are so high is suspicious -- I'd suspect some sort of engineering, because the crater walls are going to need to be high enough to be visible from over the horizon (how else do they block the sun?) and that height grows very fast as the angular size of the archipelago grows...

Potentially relevant to your interests: a town in a valley in Norway, which is dark during the middle of the day...