by the National Oceanic and Atmospheric Administration of the United States. Some of the smallest tidal ranges occur in the Mediterranean, Baltic, and Caribbean Seas. A point within a tidal system where the tidal range is almost zero is called an amphidromic point. Classification The tidal range has been classified as: Micro-tidal – when the tidal range is lower than 2 metres (6'6¾"). Meso-tidal – when the tidal range is between 2 metres and 4 metres (6'6¾" and 13'1½"). Macro-tidal – when the tidal range is higher than 4 metres (13'1½"). See also King tide, an informal term for an especially high spring tide References Tides Oceanography