merikartat

Merikartat, or nautical charts, are official representations of maritime areas that support safe navigation. They cover Finnish territorial waters and adjacent seas and include coastline, seabed depths, tides and currents, navigation hazards, aids to navigation such as lighthouses and buoys, shipping lanes, ports, anchorages, and restricted or protected areas. Charts are produced at various scales for harbor approaches and open-water navigation and are used by professional mariners as well as recreational sailors.

Content and features include depth soundings and contour lines, seabed and underwater hazards, submerged obstructions, and notes on bottom types. They also show navigational warnings, traffic separation schemes, and other regulatory or safety information, such as restricted zones and anchorages. Additional information on dredging, construction projects, and changes to aids to navigation may appear on the charts or accompanying notices.

Formats and standards: Merikartat exist in printed paper form and as digital charts, including electronic navigational charts (ENC) for use with electronic navigation systems (ECDIS). They are prepared and maintained according to international hydrographic standards set by the International Hydrographic Organization (IHO). Updates are distributed through notices to mariners and continuous digital chart updates.

Production and management: In Finland, merikartat are produced and maintained by the national hydrographic service in cooperation with authorities responsible for mapping and navigation safety. Charts are revised to reflect new hydrographic surveys, changes in depths, updated aids to navigation, and newly imposed maritime restrictions.

Usage and access: Mariners obtain merikartat through official channels; digital versions are accessible for online or offline use. They support route planning, passage execution, and safety assessments in Finnish waters and are used on ships, in port operations, and by authorities for safety and rescue planning.