"Bay Area surfers who own smart phones and tablets have been using tide apps for years. But now there's also a new current app that gives real-time and predicted info on surface currents within the Bay, and as far south as Half Moon Bay, sourced from the Coastal Ocean Currents Monitoring Program in Northern California (COCMP-NC). The data is provided by radiowave-emitting sensors.
In any case, since your tax dollars helped to fund it, and it's free, iPhone and iPad users should take a look. (Hopefully an Android version will be available soon also.)"
Source: norcalcurrents.org
