The delay of the maximums and minimums (high water and low tide) of the tide in 1 or 2 days with respect to the phases of the Moon, must be the at heart oceanic water friction. This delay also can soon be seen day due first at the time which the stars in giving a complete return take, and the friction that generate the tides according to their amplitude.

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.