The Orrery of the Inner Planes was an enchanted mechanical object, the origin of which was up for debate. Some scholars believed it to be a marid device, while others thought it to be a creation of the cooperative efforts of both the marid and dao, which seemed highly unlikely.
The Orrery of the Inner Planes looked like a large clock.
The orrery showed the relative positions of the planets, moons, and stars, as well as the junctions of the Inner Planes. In the hands of a competent navigator, the orrery could be used to travel between all of the Inner planes, including all Elemental planes, the Ethereal plane, and the Prime Material Plane.
Any ship with the orrery mounted on deck could traverse all of the elements, gliding through solid stone, "sailing" underwater, etc. Additionally, the orrery protected both the vessel and all passengers from adverse elemental effects. A ship on the Prime plane could even levitate with the orrery on board.
Incompetent navigators who attempted to use the orrery often wound up on dangerous planes of existence instead of their intended destination.