You need to know that:
(a)
Goods transported entirely or partly by water between U.S. points, either directly or via a foreign port, must travel in U.S. flag vessels that have a coastwise endorsement;
(b)
There are exceptions and limits for the U.S. Island territories and possessions in the Atlantic and Pacific Oceans (see § 102-117.155 ); and
(c)
The Secretary of the Treasury is empowered to impose monetary penalties against agencies that violate the coastwise laws.
Code of Federal Regulations
[65 FR 60061, Oct. 6, 2000, as amended at 75 FR 51394, Aug. 20, 2010]