Abstract: A ladder incorporating a vertical support structure and a set of removable rungs. The vertical support structure is formed by stacking a series of interlocking sticks. The sticks incorporate features allowing the removable installation of the rungs. The rungs are small and light, so that a set of such rungs may be easily carried by a user. The vertical sticks generally remain attached to the object to be climbed—such as a tree or pole. When the user wishes to climb the object, the user installs the rungs as he or she climbs. The rungs are then removed upon descent. In this manner, unauthorized climbing of the object is inhibited. Locking features are also included to prevent unauthorized access by another person having a set of removable rungs. Several different embodiments of the removable rungs are disclosed. The common feature of all these embodiments is the fact that the rungs cannot come loose from the vertical stick while they are under load.