This Science Plan presents the objectives, proposed work-plan, and anticipated outcomes for the National Oceanic and Atmospheric Administration West Coast Deep-Sea Coral Initiative under the Deep Sea Coral Research and Technology Program. The four-year Initiative (FY 2018-2021) is designed to work with partners to discover, map, characterize, explore, and conduct research on deepwater coral and sponge habitats in support of natural resource management off California, Oregon and Washington. The Science Plan was developed by a cross-NOAA steering committee with input from numerous partners and stakeholders.