This thesis investigates the performance of three key routing protocols—Vector-Based Forwarding (VBF), Depth-Based Routing (DBR), and Flooding—in Underwater Acoustic Wireless Sensor Networks (UWSNs). Using NS-3 with the Aqua-Sim extension, this study evaluates critical Quality of Service (QoS) metrics, including average delay, throughput, and packet loss, across diverse underwater scenarios. The findings reveal that VBF consistently achieves the lowest delay, ranging from 0.0145s to 0.0523s, outperforming Flooding (0.0342s to 0.1281s) and DBR (0.0813s to 0.1894s). In terms of throughput, VBF also demonstrates the highest values, between 1.75 kbps and 5.42 kbps, followed by Flooding at 1.21 kbps to 4.89 kbps, while DBR records the lowest throughput at 0.87 kbps to 2.64 kbps. For packet loss, Flooding exhibits the lowest rates in high-density networks, ranging from 11.40% to 30.62%, while VBF maintains moderate packet loss between 34.53% and 57.34%. DBR suffers from the highest packet loss, increasing from 70.62% to 97.26% across all conditions due to its strict depth-based forwarding decisions. These results highlight the importance of scenario-specific protocol selection in UWSNs. VBF is the most suitable for real-time applications requiring low delay and high throughput, particularly in medium-depth networks. Flooding ensures reliable packet delivery in high-density environments but introduces high delay due to excessive retransmissions. DBR, despite its depth-based mechanism, is highly inefficient in terms of throughput and packet loss, limiting its practical deployment. Future work should focus on optimizing DBR’s forwarding strategy, developing hybrid routing approaches, and incorporating energy efficiency considerations to enhance overall UWSN performance.