A system for the detection of acoustic waves in the sea comprising the following units configured to be housed on board of a sea vessel: - a source of an optical fiber cable without coating each comprising a core and a cladding; - writing means arranged to receive as input said optical fiber cable and arranged to generate as output a processed optical fiber curtain on which a plurality of optical sensors are made spaced from one another along each optical fiber with a L/N° fibers pitch; said writing means being configured for making a periodic modulation of the refractive index of the core in a permanent way, providing, for each sensor, a diffraction grating that acts as an optical filter in transmission and a selective reflector centered on a resonance wavelength λB specific for each sensor; said writing device being thus configured to obtain different resonance wavelengths λB for different sensors belonging to the same processed optical fiber; - overcoating means arranged to receive as input said processed optical fiber curtain and arranged to generate as output an optical fiber acoustic sensor; said overcoating means being adapted to cover the portion of each sensor with at least one polymer layer with a low elastic modulus in order to improve the sensitivity of the sensor to the hydrostatic pressure by modifying the original resonance wavelength λB of the refractive grating towards a shifted wavelength λB-sh; - polymerization means of the overcoating of the sensors; said polymerization means being adapted to obtain a rapid total hardening of the polymer released from the head; - deployment means suitable for being carried by the said sea vessel and adapted to release the optical fiber acoustic curtain into the sea; - a detection system of subaqueous acoustic waves comprising generating means to supply a wide-band optical signal to said optical fiber acoustic sensor and detection means to process the signals coming from the various sensors for the detection of the characteristics of acoustic waves detected in the sea; said optical fiber curtain arranged to be jointly used with said detection system; - said system further comprising programming means adapted to generate, in response to an operational need of the moment, piloting signals (P1, P2) of at least one of said writing means and overcoating means to change the optical characteristics of the optical fiber acoustic sensor according to said operational need. - a source of an optical fiber cable without coating each comprising a core and a cladding; - writing means arranged to receive as input said optical fiber cable and arranged to generate as output a processed optical fiber curtain on which a plurality of optical sensors are made spaced from one another along each optical fiber with a L/N° fibers pitch; said writing means being configured for making a periodic modulation of the refractive index of the core in a permanent way, providing, for each sensor, a diffraction grating that acts as an optical filter in transmission and a selective reflector centered on a resonance wavelength λB specific for each sensor; said writing device being thus configured to obtain different resonance wavelengths λB for different sensors belonging to the same processed optical fiber; - overcoating means arranged to receive as input said processed optical fiber curtain and arranged to generate as output an optical fiber acoustic sensor; said overcoating means being adapted to cover the portion of each sensor with at least one polymer layer with a low elastic modulus in order to improve the sensitivity of the sensor to the hydrostatic pressure by modifying the original resonance wavelength λB of the refractive grating towards a shifted wavelength λB-sh; - polymerization means of the overcoating of the sensors; said polymerization means being adapted to obtain a rapid total hardening of the polymer released from the head; - deployment means suitable for being carried by the said sea vessel and adapted to release the optical fiber acoustic curtain into the sea; - a detection system of subaqueous acoustic waves comprising generating means to supply a wide-band optical signal to said optical fiber acoustic sensor and detection means to process the signals coming from the various sensors for the detection of the characteristics of acoustic waves detected in the sea; said optical fiber curtain arranged to be jointly used with said detection system; - said system further comprising programming means adapted to generate, in response to an operational need of the moment, piloting signals (P1, P2) of at least one of said writing means and overcoating means to change the optical characteristics of the optical fiber acoustic sensor according to said operational need.