Analyzing the behavior of underwater steel pipes under explosive loading is critical due to their essential role in marine infrastructure. This study investigates the effects of underwater explosions with three different TNT masses located 5 meters from the pipe using numerical simulations in ABAQUS. The results demonstrate that increasing TNT mass leads to higher kinetic energy and strain in the pipe. Furthermore, the effectiveness of four different reinforcement configurations using GFRP sheets was evaluated. Continuous GFRP wrapping proved to be the most effective, reducing the maximum local deformation of the pipe by over 52%. Although discrete GFRP rings offered partial protection, local stresses at the ring-pipe interfaces limited their overall effectiveness. Findings also indicate that underwater explosions inflict less damage on pipes compared to air explosions, owing to greater energy dissipation in the water environment. This research provides practical strategies to enhance pipeline resistance against explosive loads and can inform the design and reinforcement of underwater pipes.