XTide is a package that provides tide and current predictions in a wide variety of formats. Graphs, text listings, and calendars can be generated, or a tide clock can be provided on your desktop.
XTide can work with the X window system, plain text terminals, or the web. This is accomplished with three separate programs: the interactive interface (xtide), the non-interactive or command line interface (tide), and the web interface (xttpd).
xtide is packaged in the main Debian archive.
xtide - Debian package
http://www.flaterco.com/xtide/ - xtide homepage