<p>The beam model is widely used in the study of maritime structures, including columns, oil platforms, and towers surrounded by water. These structures often support concentrated masses, making it critical to understand their response amplitudes during the design phase. This paper investigates a nonlinear cantilever beam immersed in a fluid, subjected to a concentrated mass and harmonic water flow. Three nonlinear terms, spanning the first four modes, are incorporated into the analysis of the response, which is calculated using the harmonic balancing technique. Using analytical methods to analyze the frequency response, jump phenomena are identified within the triple response region between bifurcation points. This jumping behavior manifests as softening in the second, third, and fourth modes, while the first mode exhibits hardening behavior. Each nonlinear term uniquely influences the system’s vibrational behavior and affects the onset of jump phenomena. Furthermore, the system temporal response, Poincaré mapping, and state-space behavior reveal distinct stability points along the phase curve. The study also explores chaos phenomena in the nonlinear beam, highlighting chaotic behavior at bifurcation points, with the geometric nonlinear term exerting the most significant impact on response irregularity. Key contributions of this research include the investigation of jump phenomena using both analytical and numerical methods, validation of findings through comparative analysis, examination of jump phenomena across the first four modes, and a comprehensive exploration of nonlinear phenomena. These phenomena encompass bifurcation and chaos, analyzed through phase curves, time responses, and Poincaré mapping. These advancements contribute to a deeper understanding of nonlinear immersed beam dynamics within the field.</p>