Fundamental key aspects of underwater acoustic communications have been taken into account to define an underwater swarm network for monitoring and exploration applications. We discuss the communication architecture of underwater sensor networks as well as the factors that influence underwater network design. Specifically, the main requirements needed to design a suitable sensors underwater system has been provided by considering a Cross-Layer solution among the lower layers of the node to maintain the power consumption as low as possible without complexity addition in the architecture design. Results show that the average power can be preserved thanks to power control implementation used to optimize the overall across the physical, Medium Access Control (MAC) and Network (NWK) layers. This study wants to provide the performance analysis of a swarm network model to provide guideline for hardware developing of swarm nodes for a real underwater application.