The National Oceanic and Atmospheric Administration (NOAA) is making available online its Raster Nautical Charts (RNC). These charts are geo-referenced, full-color images of NOAA’s paper nautical charts, published by NOAA in the .BSB format. NOAA updates the RNC for Notices to Mariners on a weekly basis. They are an official product of NOAA and meet the S-61 Standard – Raster Navigational Charts – of the International Hydrographic Organization (IHO).
Source: HK Law