The thing you are asking is often referred to as “mineral rights”. The legal ownership of what is under the surface of the property you have the legal deed for. Because this is a legal concept (ownership and mineral rights) it will depend on your country, state, municipal laws.
In rural areas people often drill a well for water. AFAIK, there are few restrictions on water rights.
If you were to dig a foundation for a home, or a pool with a deep end, or a bomb shelter you would be digging 8 feet or more below the surface. This is generally allowed as long as you pay attention to buried pipes and cables.
Latest Answers