What are minus tides?

Question

I bought a tide book and it says minus tides will be highlighted in red and I have no idea what the h**l that means.

Answer 1

i concur with answer one it is the opposite of a leap tide. a sub-zero reading.

Answer 2

Minus tides is when the level of the ocean is lower than zero.  These extreme low tides are highlighted in red so you don't mistake them as plus.

Answer 3

Tides are measured against a standard height datum (previously referred to as a 'mean sea level').  Periods of highest tide ('spring tides'), when the gravitational attraction of the sun and moon are in line, are also the periods of lowest tides (ie, the period of greatest tidal variation).  When the level of the low tide is below the standard datum level, then it is a 'minus' tide.