IHO Data Centre for Digital Bathymetry (DCDB)

The International Hydrographic Organization Data Centre for Digital Bathymetry (IHO DCDB) was established in 1990 to steward the worldwide collection of bathymetric data. The Centre archives and shares, freely and without restrictions, depth data contributed by mariners. The IHO DCDB is hosted by the U.S. National Oceanographic and Atmospheric Administration (NOAA) on behalf of the IHO Member States.

Access Data

The DCDB contains oceanic soundings acquired by hydrographic, oceanographic and other vessels during surveys or while on passage. Data are publically available and used for the production of improved and more comprehensive bathymetric maps and grids, particularly in support of the GEBCO Ocean Mapping Programme.

IHO Member States and others can contribute bathymetric data and metadata via File Transfer Protocol (FTP), email, or mail (CD, DVD, and hard drive) in the formats below. Other formats will be considered on a case-by-case basis.

  • Raw sonar data: MGD77T or the original manufacturer's format
  • Processed data: BAG, NetCDF, tiff, xyz, sd, asc, etc.
  • Metadata: XML or text

Do You Know?

  • Detailed knowledge of global bathymetry is critical for understanding how Earth's systems interact and to support coastal zone management, environmental protection, tsunami modelling, inundation forecasting, and charting.

  • The shape of the ocean basins, ridges and mountains influence the flow of sea water carrying heat, salt, nutrients, and pollutants. These features also influence the propagation of energy from undersea seismic events that result in potential disasters such as tsunamis.

  • Less than 15% of our oceans are mapped with in situ soundings, making it critical to preserve and share the data already collected and to identify and work together to fill high priority data gaps to support these important uses.

Access CSB Data

CSB Data Uses

  • Identifies uncharted features

  • Verifies charted information

  • Confirms that existing charts are appropriate for the latest traffic patterns

  • Provides data in areas where little to none exists


Crowdsourced bathymetry (CSB) is a collection of depth measurements from vessels, using standard navigation instruments, while engaged in routine maritime operations. While CSB data may not meet accuracy requirements for charting areas of critical under-keel clearance, it holds potential for a myriad of other uses.

The DCDB accepts CSB contributions (GeoJSON format: PDF; JSON) through a network of "Trusted Nodes," the organizations or individuals serving as data liaisons between mariners (data collectors) and the DCDB. Trusted Nodes supply data logging equipment, provide technical support to vessels, download data from data loggers, and transfer the information directly to the DCDB.

This cooperative approach leverages underway x, y, z, t data already being collected on vessels with common commercial echo sounders and Global Navigation Satellite System receivers.

Parties interested in becoming a Trusted Node should contact the DCDB at mb.info@noaa.gov

The IHO's Crowdsourced Bathymetry Working Group in partnership with NOAA’s Office of Coast Survey and Rose Point Navigation Systems are engaged in pilot CSB projects that have confirmed the feasibility of the CSB approach. There are also commercial and volunteer based organisations using similar methodology (e.g., Olex, TeamSurv).

Nautical Charts

IHO DCDB sounding data are used in the compilation of small scale nautical charts, especially in areas where no other surveys exist. Metadata are available from the B-4 Publication (Information Concerning Recent Bathymetric Data).

Bathymetric Mapping Projects

Data are also used for a variety of products, including the General Bathymetric Chart of the Oceans (GEBCO) and regional ocean mapping programmes, such as the International Bathymetric Chart (IBC) Series.
Data Centers

Shallow Water Bathymetry
Electronic Navigational Charts (ENC)

The IHO Circular Letter 36 of 2006 invited Member States to provide low density shallow water bathymetry for their coastal areas. To facilitate the extraction of soundings and contours from Electronic Navigational Charts (ENC) cells, a software application was developed and distributraed with CL 36 (Request Software). Only data from ENCs in navigational purpose bands 2 and 3 were requested as these best suited the requirements of GEBCO.

Policies for the use and distribution of shallow water bathymetric data are available in the IHO Circular Letter 90/2009 (17 December 2009), or contribute shallow water bathymetry by Contacting the IHO.