TotalTide is produced by the UK Hydrographic Office to provide instant tidal height and stream predictions worldwide. TotalTide uses official data from the world's premier hydrographic authorities to calculate highly accurate positions. Tidal heights for the world's Standard and Secondary Ports are displayed clearly and concisely in both graphical and tabular format. It uses the same prediction algorithms and Harmonic Constants as the Admiralty Tide Tables. Tidal Stream rates, for more than 3000 positions worldwide, are presented on a chart-based diagram.