Sandskiffs are the main form of transportation through the Shadow Fold. They are used over animal mounts as the latter are too conspicuous and frighten easily in the hostile terrain.
Shadow and Bone
A larger variant with 3 sails exists, one of which belonged to The Darkling. It was used in the Darkling's demonstration of Alina's Sun Summoner powers in the Fold to the ambassadors of the neighboring nations.