Neap tides are those tides which exhibit relatively small amounts of variation and result when the sun and moon are at right angles to each other and therefore tend to counteract each other's effect on the ocean. Spring tides, on the other hand, show the greatest tidal variation (high, high tides and low, low tides) and result when the sun and moon are in alignment with each other, in which case the effect of the two bodies becomes additive.
Okinawa* exhibits what oceanographers consider to be semi-diurnal tides, meaning there are two high tides and two low tides per lunar day. During the year 2012, Okinawa will experience two low spring tides on the 14th of December (01:26am) and on the 15th of December (02:12am), both with a value of -27cm. The highest spring tides (also two) will occur on the 2nd of August (06:41am) and the 3rd of August, both with a value of 227cm. Combined, these minimum and maximum levels result in a value of 256cm (8.4ft) of total tidal variation for the current year.
*Tide data from WWW Tide and Current Predictor for Naha, Okinawa.
