North-East Pacific Undersea Network Experiments (NEPTUNE) is a multi-node cabled ocean observatory linked by 818 kilometers of powered fiber optic cable off-shore from Vancouver Island across the northern Juan de Fuca tectonic plate. It includes a Data Management and Archive Station (DMAS) at the University of Victoria (UVic) and a shore station at Port Alberni, BC, Canada. The core of the network consists of 6 branching units, 6 node stations, 13 junction boxes and more than 130 instruments. In this paper, we explore the costs and benefits of constructing a simulator for NEPTUNE using the OMNeT++ simulation platform---a C++ based discrete-event simulator. In this context, we present the design and implementation of a simple simulator that can work with a variety of configurations of instruments, where the instruments are connected to DMAS via junction boxes and branching units, and generate TCP and UDP traffic following certain patterns. The simulator is designed for supporting \emph{what-if} scenario analysis, particularly with respect to system evaluation and discovery of limits associated with network traffic behaviors. Our study reveals that, although building the simulator in OMNeT++ has many advantages such as ease of tuning and calibration, capturing sufficient details regarding the working behavior of the actual NEPTUNE environment is still challenging. A survey of alternative tools, including NS-2/NS-3, OPNET, JiST/SWANS, J-Sim, SSFNet, and Qualnet reveals that these nuances would not be any less challenging within these simulation environments. / Graduate