Recent research on Cooperative Relaying in Wireless Sensor Networks (WSNs) has focused on improving energy efficiency, reliability, and network lifetime by enabling sensor nodes to collaborate in data transmission. Cooperative relaying techniques leverage intermediate nodes to forward data packets, reducing transmission errors and mitigating path loss. Advanced studies have explored machine learning and reinforcement learning-based relay selection strategies to adapt dynamically to network conditions such as channel fading, interference, and energy depletion. Security-aware cooperative schemes have also been proposed to defend against eavesdropping and relay misbehavior while maintaining low latency. Overall, these research efforts demonstrate that cooperative relaying significantly enhances data throughput, coverage, and fault tolerance in energy-constrained and large-scale WSN deployments.