S-57 Nautical Chart Layers | Fast, Modern Marine Navigation

Nautical charts contain many different kinds of information, from water depths to buoys, hazards, and shipping lanes. This guide explains the layers that make up a chart and what you can expect to find in each one. Object class acronyms are shown as they appear in the UI.

Floating and fixed marks that help you fix your position and navigate safely. This layer includes:

Object Class	Name	Description
`BCNCAR`	Beacon, cardinal	A fixed aid marking the cardinal direction of the best navigable water relative to a danger.
`BCNISD`	Beacon, isolated danger	A fixed aid marking a danger of limited extent that has safe water all around it.
`BCNLAT`	Beacon, lateral	A fixed aid marking the port or starboard side of a channel or route.
`BCNSAW`	Beacon, safe water	A fixed aid marking the center of a channel or a landfall, indicating safe water all around.
`BCNSPP`	Beacon, special purpose	A fixed aid serving a purpose other than navigation safety, such as marking an anchorage or cable.
`BOYCAR`	Buoy, cardinal	A floating aid marking the cardinal direction of the best navigable water relative to a danger.
`BOYINB`	Buoy installation	A buoy used for a purpose other than navigation, such as mooring or scientific instrumentation.
`BOYISD`	Buoy, isolated danger	A floating aid marking a danger of limited extent that has safe water all around it.
`BOYLAT`	Buoy, lateral	A floating aid marking the port or starboard side of a channel or route.
`BOYSAW`	Buoy, safe water	A floating aid marking the center of a channel or a landfall, indicating safe water all around.
`BOYSPP`	Buoy, special purpose	A floating aid serving a purpose other than navigation safety, such as marking an anchorage or cable.
`BUAARE`	Built-up area	An area containing a concentration of buildings and other structures.
`DAYMAR`	Daymark	A shore-based or fixed structure identifiable by shape and color, used for daytime navigation.
`DISMAR`	Distance mark	A mark indicating a measured distance along a route, such as a mile marker.
`FOGSIG`	Fog signal	A sound signal emitted in fog or reduced visibility to warn nearby mariners.
`GRIDRN`	Gridiron	A framework on the shore used to support a vessel out of the water for repairs.
`LIGHTS`	Light	A luminous aid to navigation that marks a location or danger.
`LITFLT`	Light float	A floating, unmanned structure carrying a light and used as an aid to navigation.
`LITVES`	Light vessel	A permanently moored vessel carrying a light to mark a position or danger.
`LNDMRK`	Landmark	A conspicuous natural or artificial object on land used for position fixing.
`MORFAC`	Mooring facility	An area or structure, such as a mooring buoy or dolphin, provided for mooring vessels.
`RADRFL`	Radar reflector	A device that strengthens the radar return of an aid to navigation or hazard.
`RETRFL`	Retro-reflector	A device that reflects light back toward its source, making an aid more visible at night.
`RTPBCN`	Radar transponder beacon	A beacon that responds to radar signals to provide identification and ranging.
`TOPMAR`	Topmark	A distinctive shape mounted on top of a buoy or beacon to aid identification.

Magnetic variation

Local magnetic anomalies and magnetic variation data used to correct compass readings. This layer helps you account for differences between true and magnetic north.

Object Class	Name	Description
`LOCMAG`	Local magnetic anomaly	An area where the earth's magnetic field deviates abnormally from the expected value.
`MAGVAR`	Magnetic variation	The angular difference between true and magnetic north at a charted location.

Routes and traffic

Ships' routeing systems and ferry routes

Designated traffic lanes, separation schemes, recommended tracks, and ferry or deep-water routes. This layer includes:

Object Class	Name	Description
`DWRTCL`	Deep water route centerline	The centerline of a designated route intended for deep-draft vessels.
`DWRTPT`	Deep water route part	A segment of a deep-water route.
`FERYRT`	Ferry route	A route that is regularly used by ferries.
`ISTZNE`	Inshore traffic zone	A zone between the shore and a traffic separation scheme reserved for coastal traffic.
`NAVLNE`	Navigation line	A line used to indicate a navigational limit or boundary.
`PRCARE`	Precautionary area	An area where vessels must navigate with particular caution.
`RADLNE`	Radar line	A line shown on the chart that is used with radar for position fixing or navigation.
`RADRNG`	Radar range	A circular arc used with radar for measuring distance or position.
`RCRTCL`	Recommended route centerline	The centerline of a route that is recommended for navigation.
`RCTLPT`	Recommended traffic lane part	A segment of a recommended traffic lane.
`RDOCAL`	Radio calling-in point	A location where vessels are required or advised to report by radio.
`RECTRC`	Recommended track	A track that vessels are recommended to follow.
`TSELNE`	Traffic separation line	A line separating opposing streams of traffic in a traffic separation scheme.
`TSEZNE`	Traffic separation zone	A zone separating opposing traffic lanes in a traffic separation scheme.
`TSSBND`	Traffic separation scheme boundary	The outer boundary of a traffic separation scheme.
`TSSCRS`	Traffic separation scheme crossing	A designated crossing point where routes intersect a traffic lane.
`TSSLPT`	Traffic separation scheme lane part	A segment of a traffic lane within a traffic separation scheme.
`TSSRON`	Traffic separation scheme roundabout	A circular traffic pattern where several routes meet.
`TWRTPT`	Two-way route part	A segment of a two-way route used by traffic in both directions.

Archipelagic sea lanes

Internationally designated corridors through archipelagic waters that ships may use for passage.

Cautionary notes

Areas where extra care is advised, such as charted caution areas.

Object Class	Name	Description
`CTNARE`	Caution area	An area where vessels should exercise caution due to unusual conditions or activities.

Areas, boundaries, and limits

Boundaries and limits

Areas with specific navigational or administrative meaning, such as:

Object Class	Name	Description
`ACHARE`	Anchorage area	A designated area where vessels may anchor.
`ACHBRT`	Anchor berth	A designated berth where a single vessel may anchor or moor.
`CTSARE`	Cargo transhipment area	An area designated for transferring cargo between vessels.
`DMPGRD`	Dumping ground	An area used for the disposal of dredged or other material.
`FAIRWY`	Fairway	The navigable part of a waterway that is kept open for vessel traffic.
`ICNARE`	Incineration area	An area designated for the incineration of waste at sea.
`SWPARE`	Swept area	An area that has been surveyed by sweeping to confirm a minimum depth.

Prohibited and restricted areas

Zones where entry or certain activities are limited for safety, security, or environmental reasons. This layer includes:

Object Class	Name	Description
`MIPARE`	Military practice area	An area used for military exercises, often with entry restrictions.
`OSPARE`	Offshore production area	An area containing offshore oil or gas production installations.
`RESARE`	Restricted area	An area where entry or certain activities are restricted by regulation.
`SPLARE`	Sea-plane landing area	A water area designated for seaplane takeoff and landing.
`SUBTLN`	Submarine transit lane	A lane designated for submarines transiting on the surface.

Chart scale boundaries

Boundaries that delimit where the chart's scale changes between adjacent chart coverage areas.

Hazards

Drying Line

Features that are covered and uncovered by the tide, marking the boundary between water and intermittently exposed ground.

Object Class	Name	Description
`CAUSWY`	Causeway	A raised road or path built across water or wetland.
`DAMCON`	Dam	A barrier built to hold back water.
`DOCARE`	Dock area	An enclosed wet dock or tidal basin used for berthing vessels.
`DYKCON`	Dyke	An embankment built to prevent flooding or to reclaim land.

All isolated dangers

Hazards that stand alone on the chart.

Object Class	Name	Description
`OBSTRN`	Obstruction	An object that may hinder navigation, such as a submerged structure or debris.
`UWTROC`	Underwater rock	A rock that is submerged or awash and poses a danger to navigation.
`WRECKS`	Wreck	The remains of a sunken vessel, often a hazard to navigation.

Depth information

Spot soundings

Individual depth measurements charted at a single point rather than as a continuous area.

Object Class	Name	Description
`SOUNDG`	Sounding	A measured depth at a specific point on the chart.

Depth contours

Lines joining points of equal charted depth, showing the shape and slope of the seafloor.

Object Class	Name	Description
`DEPCNT`	Depth contour	A line joining points of equal charted depth.

Depth areas

Regions of charted depth, including dredged areas. These are shown as part of the Base Display elements layer.

Object Class	Name	Description
`DEPARE`	Depth area	An area of known depth bounded by depth contours.
`DRGARE`	Dredged area	An area deepened by dredging and maintained to a specified depth.

Seabed and seafloor

Seabed

The composition and character of the seafloor.

Object Class	Name	Description
`SBDARE`	Seabed area	An area whose seabed composition has been determined.
`SPRING`	Spring	A place where water flows out of the seabed or shore.
`WATTUR`	Water turbulence	An area of disturbed water, such as tide rips or overfalls.
`WEDKLP`	Weeds and kelp	An area where seaweed or kelp grows and may foul propellers.

Submarine cables and pipelines

Cables and pipelines laid on or near the seabed, along with the areas enclosing them.

Object Class	Name	Description
`CBLARE`	Cable area	An area containing submarine cables.
`PIPARE`	Pipeline area	An area containing submarine pipelines.
`PIPSOL`	Submarine pipeline	A pipeline laid on or under the seabed.

Tides and currents

Tidal

Tidal and water-flow features that affect how water moves through the area.

Object Class	Name	Description
`CURENT`	Current (non-gravitational)	A non-tidal current, such as an ocean or river current.

Bridges and clearances

Bridges

Bridges spanning the waterway. These are shown as part of the Base Display elements layer and are used to assess vertical clearance and air draft.

Object Class	Name	Description
`BRIDGE`	Bridge	A structure spanning a waterway that limits vertical clearance beneath it.

General reference

Base Display elements

The chart's general reference layer, including coastline, land areas, shoreline construction, and land-based infrastructure. This layer includes:

Object Class	Name	Description
`AIRARE`	Airport/airfield	A land area used for aircraft takeoff and landing.
`CANALS`	Canal	An artificial waterway used for navigation.
`CBLOHD`	Overhead cable	A cable suspended above the water that limits vertical clearance.
`COALNE`	Coastline	The line where land meets water.
`CONVYR`	Conveyor	A mechanical conveyor, often extending over water for loading.
`CTRPNT`	Control point	A fixed point used as a survey or position reference.
`FLODOC`	Floating dock	A floating structure used for berthing or lifting vessels.
`FSHFAC`	Fishing facility	A structure used in fishing, such as a fish farm or weir.
`FSHGRD`	Fishing ground	An area used for commercial fishing.
`HULKES`	Hulk	A permanently moored vessel used as a store, accommodation, or breakwater.
`ICEARE`	Ice area	An area covered by ice.
`LAKSHR`	Lake shore	The shoreline of a lake.
`LNDARE`	Land area	A landmass or portion of land above the waterline.
`LOGPON`	Log pond	An enclosed water area used for storing logs.
`LOKBSN`	Lock basin	A basin forming part of a canal or lock system.
`MARCUL`	Marine farm/culture	An area used for aquaculture or marine farming.
`NEWOBJ`	New object class	A placeholder for a newly introduced object class.
`OFSPLF`	Offshore platform	A fixed structure at sea used for drilling or production.
`OILBAR`	Oil barrier	A floating barrier used to contain oil spills.
`PILPNT`	Pile	A post or stake driven into the seabed, often marking a hazard or structure.
`PIPOHD`	Overhead pipeline	A pipeline suspended above the water that limits vertical clearance.
`PONTON`	Pontoon	A floating platform or structure used for mooring or other purposes.
`PYLONS`	Pylon/bridge support	A tower or support structure for a bridge or overhead cable.
`RAILWY`	Railway	A rail line, shown where it may serve as a landmark or cross water.
`ROADWY`	Road	A road, shown where it may serve as a landmark or cross water.
`RUNWAY`	Runway	A paved strip used for aircraft takeoff and landing.
`SLCONS`	Shoreline construction	A man-made structure built along the shoreline.
`UNSARE`	Unsurveyed area	An area that has not been adequately surveyed, so depths are unknown.

Depth areas, dredged areas, and bridges are also part of this layer, but are described separately above because they are especially relevant to route planning.

Miscellaneous (Standard)

Standard miscellaneous features.

Object Class	Name	Description
`CBLSUB`	Submarine cable	A cable laid on or under the seabed.
`PILBOP`	Pilot boarding place	A location where pilots board or disembark vessels.
`SEAARE`	Sea area	A named area of the sea.
`SISTAT`	Signal station, traffic	A station controlling waterway traffic signals.
`SISTAW`	Signal station, warning	A station providing warnings such as water level or weather.
`SNDWAV`	Sand waves	Sand waves or ridges on the seabed that may reduce charted depths.
`TUNNEL`	Tunnel	A passage beneath the seabed or riverbed.

Miscellaneous (Other)

Remaining miscellaneous features, including harbor and shore facilities, land elevation, and administrative zones. This layer includes:

Object Class	Name	Description
`ADMARE`	Administrative area	A defined area used for administrative purposes, such as a jurisdiction.
`BERTHS`	Berth	A place where a vessel can moor or dock.
`BUISGL`	Building	A structure on land shown as a landmark or reference.
`CGUSTA`	Coast Guard station	A shore facility operated by the coast guard.
`CHKPNT`	Check point	A location where vessels are required to report or be inspected.
`CONZNE`	Contiguous zone	The maritime zone adjacent to the territorial sea.
`COSARE`	Continental shelf area	An area of the continental shelf with defined rights or limits.
`CRANES`	Crane	A shore or floating crane used for loading and unloading.
`CUSZNE`	Custom zone	An area designated for customs control.
`DRYDOC`	Dry dock	A dock that can be pumped dry for vessel construction or repair.
`EXEZNE`	Exclusive economic zone	The maritime zone where a state holds economic rights.
`FNCLNE`	Fence	A fence or enclosure shown as a landmark.
`FORSTC`	Fortified structure	A defensive structure shown as a landmark.
`FSHZNE`	Fishery zone	A maritime zone where a state regulates fishing.
`GATCON`	Gate	A barrier gate controlling access to a waterway or facility.
`HRBARE`	Harbour area	The area of a harbour, including its water and facilities.
`HRBFAC`	Harbor facility	A facility within a harbour, such as a terminal or quay.
`LAKARE`	Lake area	The area covered by a lake.
`LNDELV`	Land elevation	A land feature shown by elevation or relief.
`LNDRGN`	Land region	A named region or area of land.
`PRDARE`	Production area	An area used for production, such as aquaculture or mining.
`RADSTA`	Radar station	A shore station operating radar for navigation or surveillance.
`RAPIDS`	Rapids	A fast-flowing, turbulent section of a river.
`RDOSTA`	Radio station	A shore station providing radio communications.
`RIVERS`	River	A river or stream shown on the chart.
`RSCSTA`	Rescue station	A shore facility for search and rescue operations.
`SILTNK`	Silo/tank	A storage silo or tank shown as a landmark.
`SLOGRD`	Sloping ground	An area of sloping terrain shown on land.
`SLOTOP`	Slope topline	The upper edge of a slope or escarpment.
`SMCFAC`	Small craft facility	A facility for small craft, such as a marina or boat ramp.
`TESARE`	Territorial sea area	The maritime zone extending from the baseline where a state holds sovereignty.
`TIDEWY`	Tideway	A channel where tidal currents run strongly.
`VEGATN`	Vegetation	An area of vegetation shown on land.
`WATFAL`	Waterfall	A waterfall shown on a river or coast.