What are the geographical particularities of your Countries/Kingdoms/Empires ?

My setting centers around The Agohtalhann, Polar Island Kingdom isolated from the rest of the world by an extremely dangerous sea.

It's at least how the inhabitants perceive it. The Kingdom is located on an island, which is in the middle of a large lake, which is in the middle of an immense crater, itself surrounded by a continental landmass.

The crater was formed after a cataclysmic impact 400 000 years ago. The agitated waters of the lake are caused by the edges of the crater collapsing and underwater volcanic chimneys opened since the impact. On the other side, the currents prevent even the most advanced nations from reaching the landmass.

This particularity also justifies the purple colours of the sky, ice and snow around The Agohtalhann. The impact launched absurd quantities of Amethysts into the atmosphere. Reduced into microscopic dust, the Amethyst stagnated in the sky, causing the coloration. Absorbed by the clouds, it also leads to the snow having a similar shade of colour.