; (6) is not manned in compliance with manning levels as determined by the Secretary to be necessary to insure the safe navigation of the vessel; or (7) while underway, does not have at least one licensed deck officer on the navigation bridge who is capable of clearly understanding English. (b) Exceptions (1) In general The Secretary may allow provisional entry of a vessel that is not in compliance with subsection (a), if the owner or operator of such vessel proves, to the satisfaction of the Secretary, that such vessel is not unsafe or a threat to the marine environment, and if such entry is necessary for the safety of the vessel or persons aboard. (2) Provisions not applicable Paragraphs (1), (2), (3), and (4) of subsection (a) of this section shall not apply to a vessel allowed provisional entry under paragraph (1) if the owner or operator of such vessel proves, to the satisfaction of the Secretary, that such vessel is no longer unsafe or a threat to the marine environment, and is no longer in violation of any applicable law, treaty, regulation or condition, as appropriate. D Definitions, Regulations, Enforcement, Investigatory Powers, Applicability 70031. Definitions As used in this chapter, unless the context otherwise requires: (1) The term marine environment means— (A) the navigable waters of the United States and the land and resources therein and thereunder; (B) the waters and fishery resources of any area over which the United States asserts exclusive fishery management authority; (C) the seabed and subsoil of the Outer Continental Shelf of the United States, the resources thereof, and the waters superjacent thereto