The global bathymetry and topography grid at 15 Arc Sec is the latest iteration of the SRTM+ digital elevation model (DEM) where the "plus" indicates the addition of ocean bathymetry from shipboard soundings and satellite-derived predicted depths. This DEM is a global elevation grid with a spatial sampling interval of 15 arc seconds (approximately 500 x 500 m pixel size at the equator). New data consists of >33.6 million multibeam and singlebeam measurements collated by several institutions, namely, the National Geospatial-Intelligence Agency, Japan Agency for Marine-Earth Science and Technology, Geoscience Australia, Center for Coastal and Ocean Mapping, and Scripps Institution of Oceanography. New altimetry data consists of 48, 14, and 12 months of retracked range measurements from Cryosat-2, SARAL/AltiKa, and Jason-2, respectively. Onshore, topography data are sourced from previously published digital elevation models, predominately SRTM-CGIAR V4.1 between 60N and 60S. ArcticDEM is used above 60N, while Reference Elevation Model of Antarctica is used below 62S.

For more information on this dataset, see its associated publication:
Tozer, B, Sandwell, D. T., Smith, W. H. F., Olson, C., Beale, J. R., & Wessel, P. (2019). Global bathymetry and topography at 15 arc sec: SRTM15+. Earth and Space Science, 6, 1847. https://doi.org/10.1029/2019EA000658

or visit the project website here for more details.

OpenTopography enabled access to version 2.5.5 of this dataset on November 6th 2023. Previous to this date, OpenTopography was supplying V2.1