Underwater positioning system and method

An underwater positioning method, in which at least one known location acoustic transmitter and at least one known location hydrophone is provided at known coordinates and which positions an unknown point having unknown coordinates at which an unknown location acoustic transmitter or an unknown location hydrophone is provided, the underwater positioning method comprising the following steps:

• storing in advance, when the unknown point is set in each region of a plurality of regions set by dividing an underwater positioning range, a time window for a sound wave emitted from the at least one known location acoustic transmitter to reach the at least one known location hydrophone in a database for each region of the plurality of regions;
• receiving the sound wave emitted from the at least one known location acoustic transmitter with the at least one known location hydrophone;
• and
• calculating for each region of the plurality of regions a time window-applied impulse response as an inner product of the time window and an impulse response of a sound wave propagation path from the at least one known location acoustic transmitter to the unknown location hydrophone and estimating that the unknown point is located in one of the plurality of regions where an energy of the time window-applied impulse response is a maximum relative to an energy of each of the time window-applied impulse responses calculated for each region of the plurality of regions.