Skykeeps were gigantic floating fortresses created by the K'Chain Nah'ruk. These structures looked more or less like floating mountains. The could be found in either rooted (fixed to the ground) or uprooted (floating and steerable) configurations. The most famous among these skykeeps was Moon's Spawn which was appropriated by Anomander Rake as a home for his people for a time, prior to their settling in Black Coral.
After the discovery of Moon's Spawn, Osseric spent time in the fortress studying it. He determined that Moon's Spawn had been one of the K'Chain Che'Malle's skykeeps and he withdrew from the world to continue his study of the alien mechanisms. From a Jaghut tower within a warren formed by Raraku's ancient memory, he observed a total of three skykeeps travel from the north to Seven Cities. None of their inhabitants survived contact with the continent's defenders, the Deragoth.
Four Nah'ruk skykeeps were with the K'Chain Che'malle army that defended the Malazan world from the invading armies of Silchas Ruin and Scabandari Bloodeye. Companies of Tiste Andii and Tiste Edur assailed the floating fortresses to prevent them from coming to the aid of the K'Chain Che'Malle ground forces. Scabandari and Silchas, in their Soletaken Eleint forms, then brought the skykeeps crashing to the ground by unleashing the warrens of Starvald Demelain, Kurald Emurlahn, and Kurald Galain upon them.