Baltic facts and figures
Extent: The Baltic Sea covers 415,266 square kilometres, while its catchment area - at 1.7 million km2 - extends over an area about four times as large as the sea itself.
Depth: The average depth of the whole Baltic Sea is around 50 metres. The deepest waters are in the Landsort Deep in the Baltic Proper, where depths of 459 metres have been recorded.
Catchment area: In Germany, Denmark and Poland as much as 60-70% of the Baltic's catchment area consists of farmland. Forests, wetlands and lakes make up between 65% and 90% of the catchment area in Finland, Russia, Sweden and Estonia.
Population: Over 85 million people live in the Baltic catchment area - 26% of them in large metropolitan areas, 45% in smaller urban areas, and 29% in rural areas. Population densities vary from over 500 inhabitants per square kilometre in urbanised regions of Poland, Germany and Denmark to fewer than 10 inhabitants per square kilometre in northern parts of Finland and Sweden. Almost 15 million people live within 10 kilometres of the coast.
Shipping: Around 2,000 sizeable ships are normally at sea at any time in the Baltic, including large oil tankers, ships carrying dangerous and potentially polluting cargoes, and many large passenger ferries. The Baltic Sea has some of the busiest shipping routes in the world.
Table 1: Surface areas of the Baltic Sea sub-catchment areas and total run-off in 2000
| Sub-region | Surface area (km2) | Run-off in 2000 (106 m3/a) |
| Bothnian Bay | 260675 | 155480 |
| Bothnian Sea | 220765 | 124150 |
| Archipelago Sea | 9000 | 3840 |
| Gulf of Finland | 413100 | 107340 |
| Gulf of Riga | 127840 | 28750 |
| Baltic Proper | 574545 | 115580 |
| Belt Sea | 27365 | 6670 |
| The Kattegat | 86980 | 42380 |
| Total catchment area | 1720270 | 584190 |
Source: Fourth Baltic Sea Pollution Load Compilation (PLC-4)
Table 2: Physical characteristics of the Baltic Sea and its sub-basins
| Sub-region | Area (km2) | Volume (km3) | Salinity range (psu) | Max. Depth (m) | Average depth (m) |
| Baltic Proper | 211069 | 13045 | 5-10 | 459 | 62.1 |
| Gulf of Bothnia | 115516 | 6389 | 0-7 | 230 | 60.2 |
| Gulf of Finland | 29600 | 1100 | 0-7 | 123 | 38 |
| Gulf of Riga | 16330 | 424 | 6-10 | >60 | 26 |
| Danish Straits and Kattegatt | 42408 | 802 | 8-32 | 109 | 18.9 |
| Total Baltic Sea | 415266 | 21721 | 0-32 | 459 | 52.3 |
Source: Towards marine landscapes in the Baltic Sea (BALANCE interim report N. 10)
Map of the sub-basins of the Baltic Sea, as defined in the HELCOM COMBINE Manual (click image to enlarge)
