The World Trees are the tallest type of tree that put their roots on a mountain range, intake magma, surpass the atmosphere, and become even bigger. They grow mostly in the "outside" world but at least one of them is in the "known" world. The World Tree in the "known" world is only a sapling that has only enough nutrients to grow 1784 meters (approx. 1.11 mi.). When Gon climbed the tree to meet Ging, there was a nest which contained an unknown species of a huge bird.
According to the tour guide, climbing the tree is not forbidden but climbers have to pay a fee and sign a written agreement. Climbers can reach the 500 meter points with elevators or stairs. 500 meter point and above requires people to climb by themselves. Every year, there are at least 3000 people who try to climb the tree above the 500 meter point to the top, however 94% will fail to reach the 1000 meter point and are forced to climb down. Another 4% have to pay an expensive fee for a rescue operation while 1% fall to their deaths. As the result, only 30 people are able to climb to the top and return unharmed each year. No children under 18 years old are allowed to climb the tree beyond the 500 meter point unless they are a Hunter or have a special certificate. All climbers are issued a special wristband to call for help in case they get stuck but they have to wait for 10 minutes to be rescued.
- The Hunter × Hunter World Trees' concept resembles the real life world tree motif present in several religions and mythologies, like the immense mythical tree Yggdrasil from the cosmology of Norse mythology, although it does not have the same supernatural function/property.