KM15-20 was Leg 2 of the continuing long-term bathymetric mapping of the area around Kingman Reef and Palmyra Atoll, in the equatorial Pacific. The objective of the cruise was to collect all of the bathymetric, acoustic backscatter, and sub-bottom data that might be useful to support a potential submission by the U.S. under the U.N. Convention on the Law of the Sea, Article 76 [1]. The responsibility for conducting the mapping was given to the National Oceanic and Atmospheric Administration (NOAA) by the U.S. Congress, and has been implemented since 2003 through a cooperative agreement with the Center for Coastal and Ocean Mapping and NOAA-UNH Joint Hydrographic Center at the University of New Hampshire. This cruise supplements data from a prior cruise [2] to identify the morphology of the Foot of the Slope (FoS) around the northern end of the Line Islands chain. 

The cruise consisted of primary bathymetric mapping in water depths of approximately 5000m using the R/V Kilo Moana (Figure 1.2), operated by the University of Hawai‘i. The primary mapping sonar was a Kongsberg EM122 multibeam echosounder (bathymetry and acoustic backscatter), with a Knudsen Engineering 3260 chirp sub-bottom profiler, and a Bell Aerospace bgm-3 marine gravimeter. Motion measurement was provided by an ApplAnix pos/mv 320 gps-aided inertial motion unit, while sound speed profile measurements were conducted using Sippican expendable bathythermograph (xbt) and expendable conductivity, temperature and depth (XCTD) probes.