This text discusses differences in ocean tides. Along America\'s Atlantic Coast, two high and low tides occur daily. Such tides are called semidiurnal. On the north shore of the Gulf of Mexico, the tide is diurnal, meaning that it moves in and out again once a day while in the Pacific Northwest, there are mixed tides, two highs and two lows a day, characterized by significant disparity between successive tides. The site also explains flood current or flood tide, ebb current or ebb tide, and slack water or slack tide. There is a detailed discussion of spring tide and neap tide and also an explanation of the difference between riptide and tiderip.