Use constraints: Free for non-commercial purposes. Reference must be made to data source (BALANCE).

This dataset was produced by the BSR INTERREG IIIB project BALANCE. In order to produce the marine landscapes for the whole Baltic Sea large amounts of seabed sediment data were needed. The existing data, national and international, is numerous, but very diverse. Seabed sediment data was derived using different field techniques during the past decades. The seabed sediment maps from offshore and coastal areas exist in a wide range of scales from local (1:20.000) to regional (up to 1:1.000.000). Terminology and classifications vary as well, since 9 different Baltic Sea nations (and Norway) have interpreted their own data according to different national classification schemes. National seabed sediment classification categories needed to be harmonized in order to produce one classification scheme, which had to be as simple as possible, but still takes into account biological importance. The resulting classification scheme consists of five sediment classes, which can be extracted from existing data. The sediment classes applied in the mapping and modelling of the Baltic Sea marine landscapes are:

I. Bedrock.

II. Hard bottom complex, includes patchy hard surfaces and coarse sand (sometimes also clay) to boulders.

III. Sand including fine to coarse sand (with gravel exposures).

IV. Hard clay sometimes/often/possibly exposed or covered with a thin layer of

sand/gravel.

V. Mud including gyttja-clay to gyttja-silt.

In order to be displayed in the HELCOM Map Service, the map coordinate system and projection was changed from original WGS1984_UTM34N to ETRS_1989_LAEA.

For more details see: BALANCE Interim Report no. 10 "Towards marine landscapes in the Baltic Sea": http://balance-eu.org/xpdf/balance-interim-report-no-10.pdf