Gnome gliders are scenery objects which become available for use as a means for transportation after completing the Grand Tree quest. They are able to fly the player to other hubs quickly, and are useful for getting around RuneScape Classic. All of the two-way hubs return back to the top of the Grand Tree before a you can choose between the four available destinations. The gliders examine text is "i[sic] wonder if it flys[sic]".
These locations allow travel in both directions:
This flight will crash land and the player will be unable to return to the Grand Tree: