Bathymetry mapping cruises were conducted over the past five years, and it is estimated that the majority of the sanctuary is now mapped. This advancement in documenting the Sanctuary includes the complete mapping of Penguin Bank, an important habitat for humpback whales in Hawai`i. The characteristics of the area, bound by Maui, Moloka`i, Lana`i, and Kaho`olawe, along with the extension of the shallow Penguin Bank southwest of Moloka`i, represents a unique, semi-enclosed, shallow protected sea in the midst of an expansive ocean. In 1997, at the time of the initial Sanctuary Environmental Impact Statement and Management Plan, very little information had been published about the specific characteristics of this inter-island area. The bathymetry collected during a research cruise in 2005 was added to the synthesis in order to make a preliminary assess-ment of seafloor characteristics across the state. The synthesis, begun by Hawai`i Under-water Research Lab (HURL), incorporates data from a wide variety of mapping groups and includes academic, state, and federal data.