Maritime operations are inherently distributed and involve systems and assets that are geographically dispersed across all domains of sea, land, air and space. Designing a communication relay network to support and facilitate mission command and control (C2) over large geographic areas is an important part of the mission planning and execution process to enhance the overall mission success of multi-domain maritime operations. In this paper, we study a topology design problem in which the C2 nodes located in different domains (land, ocean surface and underwater) are linked via a communication relay network. The objective of this research is to evaluate, characterize and perform a trade-off analysis on various relay network configurations consisting of underwater, surface, above-water and satellite nodes. We use a multiple-model approach in which packet-level network simulations are combined with network flow and queueing models to characterize the connectivity and traffic metrics of a given network topology configuration. We develop a custom simulation tool named TOMO-sim, which includes network configuration generation incorporating acoustic and radio frequency (RF) propagation models, discrete-event network simulation based on SimPy framework and wsnSimpy, and a global transmit scheduler to explore efficient transmission packing, to gather detailed simulation evaluations on configurations. Network flow and queueing models provide additional insight into network connectivity and traffic flows under simplifying assumptions and are useful to perform sensitivity analysis. Our study demonstrates that adding assets, such as underwater nodes and gliders, only improves performance when they are well-placed according to the complex acoustic propagation environment.