Laser-generated ultrasonic guided and bulk waves are increasingly considered for the nondestructive testing (NDT) and structural health monitoring of engineering systems. Methods based on the use of pulsed laser or continuum laser are ideal when a non-contact approach for the generation of stress waves is desired. This paper presents the initial progresses of an ongoing study where a pulsed laser is used to generate stress waves in underwater structures. In particular, in this paper we show the results of one experiment that investigates the effect of water temperature on the ultrasonic energy propagating through one immersed test specimen. We first studied the effect of water temperature on the amplitude of the laser-generated waves. Then, we conducted a cross-correlation analysis on the waveforms to assess their similarity. Finally, we performed a frequency analysis to investigate the frequency content of the laser-generated bulk waves.