Indian Ocean sea floor topography, satellite image. This map combines cloud-free satellite images on land with detailed ocean depth measurements (bathymetry) for the oceans. Ocean depth is colour-coded from blue-white at sea level to dark blue in the deep ocean plains and trenches. The bathymetry data combines satellite radar altimeter data and ship surveys from the GEBCO (General Bathymetric Chart of the Oceans) Digital Atlas. The land satellite imagery is from the AVHRR (Advanced Very High Resolution Radiometer) sensor on the NOAA Polar Orbiter weather satellites. Lakes and rivers are overlaid from a digital map.