With this final rule, the National Oceanic and Atmospheric Administration (NOAA) is allowing the United States Coast Guard (USCG or Coast Guard) to carry out certain otherwise prohibited activities within waters of Greater Farallones National Marine Sanctuary (GFNMS) and Cordell Bank National Marine Sanctuary (CBNMS) beyond approximately 3 nautical miles (nm) from the shore, in the areas of the sanctuaries that were expanded in 2015. This final rule will further the ability of the USCG to complete its mission requirements and NOAA's policy of facilitating uses of the sanctuaries to the extent compatible with resource protection. There is no change to the regulatory prohibitions or exceptions applicable to the pre-expansion boundaries of the two sanctuaries. NOAA published a proposed rule and draft environmental assessment (EA) under the National Environmental Policy Act (NEPA) on November 22, 2017. NOAA received written and oral public comments on the proposed rule and draft EA, and NOAA considers and responds to the comments in this final rule and the final EA.