The term 'shore phenomenon' refers to the regular rise and fall of the ocean's water level along the shoreline. This phenomenon is caused by the gravitational pull of the moon and sun, and is known as the TIDE. The two main types of tides are high TIDE and low TIDE, with a third type known as neap TIDE occurring in between. High TIDE is when the water level is at its highest, while low TIDE is when the water level is at its lowest. Neap TIDE is when the difference between high and low TIDE is at its smallest.