Open Waters

Hi!

Open Waters is a community for mariners, developers, and ocean enthusiasts. My hope is that this community can create better tools to understand and navigate the sea through open collaboration.

The ocean is a commons. We all depend on it, and we've all benefited from centuries of mariners, hydrographers, and scientists sharing what they learned. Open source works the same way: freely sharing what we build makes the tools better for everyone. Everything here is open, and contributions are welcome from anyone.

Learn more at openwaters.io, or get in touch. If you'd like to support the work, you can sponsor me on GitHub.

Cheers!
– @bkeepers

Tide and current predictions, offline, on every platform, powered by the open Slackwater prediction engine and station database.

• iOS — iPhone, iPad & Apple Watch
• Android — the Android app (in development)
• Libraries — the prediction engine for TypeScript and Swift
• API — hosted HTTP API for tides and currents
• Database — a public database of tide and current stations
• Signal K Plugin — tide and current predictions for your vessel's position
• Homebrew — brew install the Slackwater command-line tool

• almanac — an offline sun & moon engine: positions, rise/set, twilight, moon phase, eclipses. Twin Swift and TypeScript ports.

• Open Waters AIS — live vessel traffic from open government feeds and volunteer receivers: a live map, aisstream.io-compatible streams, a REST API, and an MCP server. Contribute your receiver's data, or build on the aiscast source and Signal K plugin.

• seamap — a nautical-themed map with depths, seamarks, and hazards (view it)
• seascape — a map of the seafloor built from global open bathymetry (view it)
• OpenWaters — an experiment in modern marine charts (alpha — not for navigation)
• chart-catalog — a catalog of freely redistributable electronic navigational charts, pre-baked as vector tiles
• enc-tiles — tools to produce vector tiles from Electronic Navigational Charts
• tile-fonts — SDF glyph stacks for the Open Waters map styles

• crowd-depth — collect and share depth soundings from your vessel with crowd-sourced bathymetry programs

• maritime-zones — offline where-am-I and distance-to-territory lookups over the Marine Regions maritime boundaries, as FlatGeobuf tiles

• openwaters.io — the website
• slackwater.xyz — the Slackwater landing page
• status — status page and uptime history for Open Waters services, live at status.openwaters.io

• noaa-water-level-research — a reproducible evaluation of NOAA water-level forecasts against explicit accuracy criteria
• chs-current-validation — year-round validation of Slackwater's fitted current predictions for Canadian stations

Whether you're a developer, a mariner with domain knowledge, or someone who just loves the ocean, there's a place for you here. Browse the repos, open an issue, join the Discord, or say hello.