This manual contains the International Regulations for Prevention of Collisions at Sea, 1972 (72 COLREGS). It also contains the Inland Navigation Rules, which enacted by law on 24 December 1980 and became effective for all Inland waters except Great Lakes on 24 December 1981. The Inland Rules became effective on the Great Lakes on 1 March 1983. Some differences do remain between the International and Inland Rules. The side-by-side presentation of the Rules in this publication will allow mariners to determine those differences.