From September 23 October 14, 2023 (Seward, Alaska to San Francisco, California), NOAA Ocean Exploration completed Seascape Alaska 6: Gulf of Alaska Transit Mapping (EX2307). Operations during this 22-day expedition included collection of 47,899 square kilometers of seafloor bathymetry (40,108 in the U.S. Exclusive Economic Zone). During mapping operations, NOAA Ocean Exploration simultaneously collected EM 304 multibeam sonar bathymetry observations and Simrad EK60/EK80 split-beam fisheries sonar observations of biologic material in the water column, as well as Knudsen 3260 sub-bottom profiler observations of sub-seafloor geologic structure and sediment. Focused survey regions included closing bathymetric gaps in the Gulf of Alaska, California, and off the coast of British Columbia, Canada. An additional focused survey in the Cascadia margin off the coast of Washington improved data quality in a region of interest for geological hazards. The exploratory mapping operations conducted during this expedition provide initial characterization of the region, as well as data to support further exploration. All data associated with this expedition have been archived and are publicly available through the NOAA archives.