Ocean Depth Map: Sea Depths

See the approximate water depth under you, anywhere on the ocean. Ocean Depth Map reads your phone's GPS and shows the sea depth at your position as one big number, in feet, meters or fathoms. The chart around you is shaded by depth, with labeled depth lines, so banks, channels, drop-offs and deep water stand out at a glance. • Depth under your GPS position, updated as you move • Depth chart with shaded depths and labeled depth lines • More detail in US coastal waters, from NOAA survey data (cells about 30 m across) • Tap the chart, or drag the marker, to read the depth anywhere; each reading names its source and cell size • NOAA nautical charts in US waters (switch it on in Settings) • Works offline in areas you have viewed; save an area to keep its depths at every zoom • Feet, meters or fathoms • An arrow shows which way you are heading Where the depths come from Worldwide, depths come from the GEBCO_2026 Grid, a global model of the sea floor (GEBCO Compilation Group (2026) GEBCO_2026 Grid). Its cells are about 450 m (a quarter mile) across, so the number is an average for that area, not a sounding. In US coastal waters the app adds NOAA BlueTopo, NOAA's National Bathymetric Source, resampled to cells about 30 m (100 ft) across. Both can be far off near shore, over reefs, rocks and sand banks, and in narrow channels, and even detailed data can miss rocks, reefs, coral heads and wrecks. Depths are relative to about mean sea level, with no tides. Lakes and rivers are not covered. NOT FOR NAVIGATION. Use official nautical charts, your boat's depth sounder and local knowledge to navigate. Privacy: your exact position is never sent or stored. The chart downloads map pieces for the area on screen. The app is free, with one small ad at the bottom. Ocean Depth Map is not affiliated with or endorsed by GEBCO, the IHO, the IOC or NOAA.

More detail: in US coastal waters the depth chart now uses NOAA survey data, resampled to cells about 30 m across, on top of the 450 m global grid. Each reading names its source and cell size. Saved areas with detail take more space. Still approximate and not for navigation: even detailed data can miss rocks, reefs, coral heads and wrecks.