Map Symbols for Water Bodies: Wavy Blue Lines

Standard Cartographic Convention

On maps, water bodies (rivers, streams, lakes, reservoirs, oceans) are represented by blue lines or polygons.

Specific Symbols

• Rivers/Streams: Blue lines — solid for perennial, dashed/dotted for intermittent. Width often indicates size/order.
• Lakes/Ponds/Reservoirs: Blue polygons (filled areas) — outline + blue fill/tint
• Coastlines/Oceans: Blue tint/shading offshore; coastline line
• Canals: Blue lines, sometimes with lock symbols
• Wetlands/Marshes: Blue stipple or special pattern

Flow Direction

• Arrow on line (small triangle) or "V" notches pointing downstream
• Contour lines crossing stream form "V" pointing upstream (rule of V's)

Standards

• USGS topographic maps
• Ordnance Survey (UK)
• OpenStreetMap / Google Maps (blue vector tiles)
• ICAO / nautical charts (specialized symbology)

Blue = water is near-universal in modern cartography.