As a result, all vessels have engaged in the coastwise trade have been required to be coastwise-qualified (i.e., U.S.-built, owned, and documented). Under the Passenger Vessel Services Act of 1886 (46 USC § 55103), non-coastwise-qualified vessels cannot transport passengers directly between U.S. ports. Generally, a passenger is any person carried on a vessel who is not directly and substantially connected with the operation of such vessel, its navigation, ownership, or business. The precise definition of what constitutes a U.S. port ("coastwise point") includes artificial islands and similar structures, as well as to mobile oil drilling rigs, drilling platforms, and other devices attached to the seabed of the Outer Continental Shelf for the purpose of resource exploration operations, and the anchored warehouse vessels that supply drilling platforms.