Section 5. When operating in the waters of the commonwealth, a tank vessel shall travel only within a recommended vessel route designated by the United States Coast Guard, unless no such recommended vessel route has been designated or unless special circumstances make travel outside a recommended vessel route necessary in order to avoid an imminent navigational hazard. When operating in the waters of Buzzards bay, a tank vessel shall travel only within the designated vessel route as appearing on the National Oceanic and Atmospheric Administration chart for Buzzards bay, or as designated by the United States Coast Guard or unless special circumstances make travel outside a recommended vessel route necessary in order to avoid and imminent navigational hazard. Any person who violates this section, or an order or regulation issued or adopted hereunder, shall be subject to a civil penalty not to exceed $25,000 for each such violation.