33 CFR § 165.114 - Safety and Security Zones: Escorted Vessels—Boston Harbor, Massachusetts.
(a) Location. The following waters within the Boston Captain of the Port Zone, 1000 yards ahead and astern, and 100 yards on each side of any designated escorted vessel, are established as safety and security zones: All waters of Boston Inner Harbor, including the waters of the Mystic River, Chelsea River, and Reserved Channel west of a line running from Deer Island Light, at position 42°20′25″ N, 070°57′15″ W, to Long Island, at position 42°19′48″ N, 070°57′15″ W, and west of the Long Island Bridge, running from Long Island to Moon Head.
(b) Escorted vessel definition. For the purposes of this section, escorted vessels operating in Boston Harbor include the following: Any vessels deemed to be in need of escort protection by the Captain of the Port, Boston for security reasons.
(c) Regulations.
(1) In accordance with the general regulations in §§ 165.23 and 165.33 of this part, entry into or movement within this zone is prohibited unless authorized by the Captain of the Port Boston.
(2) All vessel operators shall comply with the instructions of the COTP or the designated on-scene U.S. Coast Guard patrol personnel. On-scene Coast Guard patrol personnel include commissioned, warrant, and petty officers of the Coast Guard on board Coast Guard, Coast Guard Auxiliary, local, state, and federal law enforcement vessels.