About Slackwater

Slackwater is a tide and tidal currents app built by Open Waters, published by Open Water Software LLC. It helps people check high and low tides, current speed and direction, and slack-water times when planning time on the water or at its edge.

The app runs on iPhone, iPad and Apple Watch. Tide stations are available around the world; current stations cover the US and Canada. Coverage varies by place. The station directory lets you browse the stations published on this website. The website and app do not have identical coverage.

Tide charts, current predictions, station search, favorites and home screen widgets are free, with no account or ads. Optional Premium adds alerts, station calendars, lock-screen widgets and Watch complications. Bundled stations work offline. Supported Canadian stations need initial setup, and some passes require a connection.

Slackwater's app source code is public under the GPL. The accuracy report explains published prediction comparisons and their limits. Predictions are not observations: weather and river flow affect real conditions. Slackwater is not for navigation.

Download Slackwater, contact us for help, or read the privacy policy for how the app and website handle data.

Mailing address

Open Water Software LLC, 411 Walnut St #15547, Green Cove Springs, FL 32043, United States. This is the mailing address published by Open Waters. For app support, email slackwater@openwaters.io.