The dataset available and suitable for this problem is NOAA's ETOPO1 1 arc-minute global relief model of Earth's surface that integrates land topography and ocean bathymetry. ETOPO1 is built as an aggregate of multiple datasets providing higher resolution of bedrock layers (up to 1 arc second) in certain coastal areas. Custom grids can be extracted by using NCEI's WCS Client.d This data source was useful because custom grids for higher resolution areas were available for extraction. This saved some time in cutting the global grid into tiles and then extracting the tiles based on the correct layer. It was also helpful to see the tiles extracted as a lat/long bounding box and referenced with a basemap.