How does Greywater Watch keep moving?

Thanks for the A2A. Greywater Watch is the seat of House Reed, and the people who live in that swamp territory are called crannogmen. Greywater Watch isn't a massive stone castle like Winterfell, but a large fortified crannog. Simply put, a crannog is a (Scottish/Irish) settlement that is built as an artificial island. read more

Greywater Watch is in the Neck, which is a swampy, boggy bit of land that separates the North from the rest of Westeros. It's implied that the structure is floating or otherwise independent of any solid ground (being in a bog), and that's how it's able to keep moving. read more

I also think that the moving of the castle can be accounted for by the idea of Aether, and time moving circularly rather than linearly, at localised points, like Valyria, the Sorrows, Braavos and Greywater Watch, within a contained sphere. read more