The astronomical tides of the Pacific Coast of Costa Rica are dominated by the Moon, and since this takes 24 hours and 50 minutes in giving a complete return to the Earth, approximately every 12 hours a high tide (high water) in both Earth sides takes place: the one when moon this on a determined point, and the other when it is in the opposite position. These tides are called semidiurnal. But, like the Moon it does not complete a return during a solar day (24 hours), the cycles of tides (high tide and low tide) are delayed every day between 40 and 50 minutes, which as large as depends the tides and on the friction that they generate at heart.

The tide in the Caribbean is basically diurnal, with main component to pave, and Lunar influence (semidiurnal inequality). By this the tide of the Caribbean coast is called mixed.

The tide ranks (difference between the high water and low tide) are very different for both coasts of Costa Rica, whose difference has to do with the marine bottom and the form in which the tide in both ocean basins oscillates. The tide rank average in our Pacific Coast is of 2,80 meters and in the Caribbean of 0,30 meters.