From Keygemin Wiki

Una is a world of floating islands called skylands. Islands in the sky. Skylands have within them a massive core made of Gemin. These cores influence the environment, biome, and materials that make up the skyland. During the period of time the skyland platter forms, the stone that collects around the core is determined by the core's aspect.

For example, an orange aspect Gemin may form skylands make of hard stones resistant to force. A blue aspect Gemin may form an skyland with many lakes, or rivers that empty waterfalls into the clouds below. Such waterfalls are feed by water generated by the skyland core itself. Una has no oceans, and rivers only appear on skylands. Their waters are bellowed from Blue Gemin deep within them.

The maximum skyland width is about 500 argoknots (490.91mi). Skylands of larger sizes are made of strong stone like granite. This is the upper limit an skyland can grow before it will break apart, or fall from the sky. skylands can sink, lift, split, drift, and plummet. The wind eventually pushes skylands around and away from each other.