, peak
amplitude indicated by color. White lines are
cotidal lines spaced at phase intervals of 30° (a bit over 1 hr).
Amphidromic points are the dark blue areas where the lines come together. These are amphidromic points, NOT tidal ranges. Tidal ranges can vary from 4 to 10 times what's marked on this map. The typical tidal range in the open ocean is about – mapped in blue and green at right. Mean ranges near coasts vary from near zero to , with the range depending on the volume of water adjacent to the coast, and the geography of the basin the water sits in. Larger bodies of water have higher ranges, and the geography can act as a
funnel amplifying or dispersing the tide. The world's largest mean tidal range of occurs in the
Bay of Fundy, Canada (more specifically, at
Burntcoat Head, Nova Scotia). The next highest, of , is at
Ungava Bay, also in Canada, and the next, of , in the
Bristol Channel, between England and Wales. The fifty coastal locations with the largest ranges worldwide are listed 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==