During the astronomical tides in the Pacific Coast of Costa Rica occurred extraordinary, whose maximums appeared the 30 of March (Full Moon the 28) with 3,20 ms (calculated with respect to a virtual point out to sea) and in second half of the year it happened the 9 of October (New Moon the 6) to 3,29 ms (referred tides to Puntarenas). These tides represent the principles of the cycle of the 4-5 years.

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

Although the distance between the Earth and the Moon are the most significant factor for the tides, the position of the three stars also is of consideration. In Full Moon, when the Moon is in opposition (the Moon in a side or end, the Earth in the center and the Sun in the other), the force of attraction of both is added and the tides are higher. These tides are called alive tides or of sicigia.

The same happens in New Moon, when the Moon is between the Earth and the Sun. Greater attraction is on the Earth side, but also smaller force will be on the other side, producing a high tide also here by the centrifugal Earth force. On the contrary, when the Moon is in quadrature (first quarter or third quarter), the force of gravitational attraction of the Sun and the Moon is contrary and the tides are small. These tides are called dead tides.

The influences are added twice each year. The distance and the position of the Moon and the Sun, with respect to the Earth, agree to favor the alive tides more discharges of the year in the equinoxes. Then the equinoctial tides of sicigias occur.