33 C.F.R. § 147.833

(a) Description. Na Kika FDS, Mississippi Canyon 474 “A” (MC 474 “A”), located at position 28°31′14.86″ N, 88°17′19.69″ W. The area within 500 meters (1640.4 feet) from each point on the structure's outer edge is a safety zone. These coordinates are based upon [NAD 83].

(b) Regulation. No vessel may enter or remain in this safety zone except the following: (1) An attending vessel;

(2) A vessel under 100 feet in length overall not engaged in towing; or

(3) A vessel authorized by the Commander, USCG Heartland District.