Tides are just really, really, long waves. Consider the M2 tide, which has a period of about 12.5 hours. This tide propagates around the world's oceans, which have a depth on the order of 4 km (for the most part). Compute the wavenumber and the wavelength for this wave. Compare it to the horizontal length scale (very roughly approximated) of the major world oceans. Does your answer make reasonable physical sense? Why or why not