Neap tide is a type of tide that occurs twice a month when the difference between high and low tide is at its least. It is caused by the alignment of the sun, moon, and earth, and is usually associated with lower than average water levels. EBB tide is the opposite of NEAP tide and occurs twice a month when the difference between high and low tide is at its greatest. It is also caused by the alignment of the sun, moon, and earth, and is usually associated with higher than average water levels. NEEP tide is a type of tide that occurs once a month when the difference between high and low tide is neither at its least nor at its greatest. It is also caused by the alignment of the sun, moon, and earth, and is usually associated with average water levels.