Hot air balloons for faster travel

All of the items needed to build a hot air balloon are already in the game. (Silk, Bamboo, fire)

Once built, the hot air balloon would rise as long as the fire was running and would drop when you put the fire out. In order to keep it simple, balloons could travel away from the sun, or west in the morning and east in the afternoon. The speed could be at run speed, but you would be able to go in straight lines, making exploring much faster.