A submersible fluorometer (10), includes: an excitation module (40) for exciting the fluorophore; and a detection module (42) for detecting the light emitted by the excited fluorophore, wherein the excitation module (40) includes a first light source (44) including a first UV LED and having a first wavelength lower than 300 nm, the excitation module (40) includes a second light source (46) including a second UV LED and having a second wavelength lower than 300 nm, the first and second wavelengths being different from each other, and the fluorometer includes an electronic circuit having a plurality of printed circuits positioned one below the other.