Flight Wood

Flight Wood is special wood that is lighter than air. It is made from the rare fleeting trees high up in the mountains southwest of El-Moleth. Its main application is hover boats. These, usually small, crafts use sails to carry passengers with exceptional speed. Flight Wood is also used for transporting heavy goods with relative ease. The heavy goods are loaded in conventional looking crates, barrels, or other containers made out of Flight Wood.
  According to the Air Genasi of Dusqa and El-Moleth, the Flight Wood simply wants to return to whatever altitude it grew on. The Gnomish inventor Myriam Liner found that this was largely true but also caused misconceptions. Myriam discovered that while growing the shoot compensated its buoyancy for the root system. Which is why the wood tends to float away when cut. The wood becomes even more buoyant after drying, as water makes way for air.
  Flight Wood isn't very durable. It requires proper maintenance, which requires specific knowhow. Damaged and untreated Flight Wood breaks apart easily so it is expensive and usually handled by professionals.