When the Sun, Moon and Earth all line up at new or full moon(as in the picture) then we get the highest(and indeed lowest) tides which are called spring tides to do the time In fact it takes a bit with to move, of time for the enormous mass of water couple of so the spring tide will actually occur a days after the new moon Because of the tilt of the earth on its axis, at the equinox sun appears to be over the equator and is a new or the same then all the forces contrive to create the highest of high tides and if the moon is also at perigee to the earth in its orbit) then that will produce the biggest tides of all.