Spelljamming Ship

A Spelljammer or Spelljamming Ship was a type of magically powered vessel that could travel great distances, even into The Astral Sea . Each ship had a magical helm or "captains-chair" that allowed a suitably powerful mage to pilot the ship. Some spelljammers were also capable of traveling to other planes of existence. Spelljammers varied enormously in design, but many contained common elements. One such element that was present in a variety of spelljammers were fan-shaped sails,  whose purpose was to harness the flow of the phlogiston, or, if within a planet's atmosphere, the wind. The size of spelljammers was typically measured as their "tonnage", which reflected the volume occupied by a ship in spatial tons and was different from the typical tonnage of seafaring ships. One spatial ton was equivalent to a volume of 100 cubic yards (76 cubic meters). 

When traveling through the emptiness of wildspace or the flow of the phlogiston, away from large objects, spelljammers could reach a top speed of 100,000,000 miles per day (6,800,000 kilometers per hour). This meant that a trip from Astara to Neoma: Moon of Astara could be completed in just over an hour, the Sun could be reached in three days. These high speeds, also called "spelljamming speeds", could not be maintained in the vicinity of a gravity plane or inside an atmosphere. Whenever approaching an object at least 10 spatial tons, or 1,000 cubic yards (760 cubic meters) in volume, spelljammers immediately decelerated to much slower speeds, which were usually determined by the ship's size, the quality of the helm, and the pilot's magical capabilities. 

Spelljammer ships are extremely rare, priceless, and represent the peak of technological achievement.