The invention relates to a device enabling an alarm to be triggered in the event of a fall into a swimming pool, and preventing false alarms caused by disturbing elements such as the wind. Said device consists of a probe (1) which is submerged in the liquid used to retransmit the aquatic waves varying in pressure in the compression chamber (8), a piezoelectric-type sensor (2) which is located inside said chamber and used to convert the pressure variations into electrical voltage, another identical sensor (3) located in the housing (7) and enabling the electronic card (4) to substract the two sets of information enabling the vibrations, in addition to the noise caused by the wind on the housing, to be eliminated, and an electronic card (4) which is used to control a siren for alerting the parents. The inventive device can optionally pilot a radio emitter (5) for controlling a deported siren.