In Beasts of Bermuda, the ocean rises and falls on an hourly clock to simulate tides. It does so Sinusoidally, typically with the difference between high and low tide being seven meters. The [Maps|maps] and caves are often designed with this mechanic in mind, allowing terrestrial animals passage only during certain times of the tidal cycle. During high tide, many land bridges on the maps will be submerged such that players who wish to cross from one part of a map to another will be at risk to attack by sea creatures.
A blog post was written on the topic here during the creation of the game.