Load official NOAA ENC cells to use depth, routing and a vector chart with no signal. Download the zip for a cell from charts.noaa.gov (e.g. US5SEAGK Shilshole/West Point, US5WA12M, US5WA13M, US5WA14M Seattle) and drop it here. Parsed in the browser (ISO 8211 / S-57), stored in IndexedDB.
Official NOAA ENC charts, charted depth under the boat, tides, and automatic water routing for Puget Sound. Charts and depth data are for planning only; never rely on a phone for primary navigation.
Chart tiles: NOAA ENC Online. Depths: NOAA ENC Direct (metres below MLLW). Tides: NOAA CO-OPS. Your position never leaves the device.