WebCalTides is a free service that provides tides, currents, solar and lunar calendars for your favorite tide stations. Data is pulled from NOAA (US/etc) and DFO-CHS (Canada). Just search for a station, then click the webcal link to subscribe. Works on Apple iCal, Google Calendar and Outlook, maybe others.
Written by Jordan Ritter, with contributions from Paul Schellenberg to support Canadian stations. Project source at GitHub.
Update 5/2025: You can now de/select whether or not to include solar events in the tide calendar, via the download dropdown.
Update 5/2025: WebCalTides can now incorporate lunar calendars too, selectable via the download dropdown.