Well... That is an interesting question. Ocean waves are kind of complex. Of course, like any other waves, their speed, wavelength, period... Are connected. The other thing to take into account is the depth of the ocean or lake. There are other complex parameters such as the height of the wave. Two waves can have the same wavelength, but can vary in height... The higher one is more energetic and move slightly faster than the less energetic one, so their periods are different... So there is no linear rule between wavelength and period. This is not true for electromagnetic waves! Moreover, equations are not simple and depend on the type of waves. For exemple, tsunami waves are not sinusoids... And I still can't understand why. However, this is a graph that can answer your question, valid for wind waves, showing different values depending on the depth of the ocean floor. [image: 20190111-101044.jpg] L is wavelength in m D is the depth in m Period is in seconds And this is an other graph showing frequencies of different ocean waves... You can see that tide waves are the most energetic ones! Their wavelengths can be over 6000km. [image: Screenshot-20190111-092848-Drive.jpg]