Subterranean termite tunnels on a block foundation in a crawl space under a building. These tunnels, built by the workers, are the highways termites follow to and from the wood in your home or business, and connect to other parts of the termite colony. Tunnels are air and water tight, providing the termites ideal living and traveling conditions. Termites can build these tunnels as high as they want as long as they can build on some support. I have found tunnels going from the ground up to the fifth floor of a beach front hotel.