Which of the following is NOT subject to real property ownership rights?

Navigable rivers running through the land are generally not subject to real property ownership rights because they are considered to be part of the public domain. The principle of public trust doctrine dictates that navigable waters are accessible for public use and cannot be owned privately. This means that landowners do not have exclusive rights to the water or the riverbed underneath, as these waterways are deemed to belong to the state or the public at large for purposes such as navigation, fishing, and recreation.

Conversely, buildings located on the property, air space above the property, and easements running with the land are all elements of real property ownership rights. Buildings are structures that owners have the right to possess and utilize. Air space above a property is considered part of the property as well, giving the owner rights to that space for various uses, potentially extending to things like air travel and aerial installations. Easements are legal rights to use another's land for specific purposes, which also run with the land—meaning they persist even if the property is sold. These aspects demonstrate the range of ownership rights that come with real property, highlighting why the navigable rivers are distinct in their ownership status.