Urban exploring is not always above ground. A popular UE is “draining” where you venture through miles of tunnel systems that are normally unseen by the majority of people. This is not my cup of tea due to the dangers of draining. However, I have been in tunnels that lie under Portsmouth. As I understand it, myself and 3 others are the only explorers to ever get in. Wiltshire also has miles and miles of underground mines which I have spent many a weekend down with the Crew.