Criminal activity is increasingly entering the ocean subsurface with acts such as illegal fishing and narco-submarining becoming points of contention. This among other illicit acts taking place in this domain imply a need for surveillance to render these activities apparent. However, subsurface Underwater Sensor Networking which is central to the surveillance is still generations behind terrestrial networking, therefore it is still challenging to monitor for subsurface activities. This is since the current signal transmission standard, acoustic communication, is limited in practical bandwidth and thus channel data-rate, this is, however, caveated with omni-directional propagation and supreme range rendering it reliable but incapable of carrying video or other data intensive sensor information. There is, however, an emerging technology based on optical (visible light) communication that can accommodate surveillance applications with superior data rates and energy savings. This investigation demonstrates how theoretically it is possible to achieve a network of underwater channels capable of sustaining a multimedia feed for monitoring subsurface activity using modern optical communication when in compared to an acoustic network. In addition, a simple topology was investigated that shows how the range limitations of this signaling can be extended by adding floating relay nodes. Through simulations in Network Simulator 3 (NS-3)/Aquasim-NG software it is shown that Visible Light wireless communication in visible light networks have a channel capacity high enough to carry out monitoring in strategic areas, referencing, optical modems that are available in the market. This implies that data-rates of 10 Mb/s are possible for the real-time video surveillance.

Pervasive computing has transformed society, and there is a desire to extend this mass data connectivity to the ocean, implementing an Underwater Internet of Things (UIoT), especially by energy companies seeking real-time sensor data from assets such as oil wells and pipelines. As evidenced by the Deepwater Horizon, Piper Alpha, and other disasters, failure of these assets can result in disaster. To avoid these risks, energy companies are interested in using Underwater Wireless Sensor Networks (UWSN) to achieve real-time asset monitoring, allowing for proactive maintenance. Generally, acoustic transmission technology is utilised to communicate with emerging ad-hoc UWSN, an established technology characterised by large coverage areas and reliable connectivity at the expense of high energy consumption and low operational bandwidth. Given that it is impossible to increase the speed of sound without altering the underwater channel itself physically, maximising end to end delivery time in each scenario is largely dependent on the hardware design involved and the selected protocol on the network and data link layers as well as the physical topology of the network. This simulation driven investigation aims to establish how routing technique and topology choice effects end-to-end delivery times in populated, active deep water oil drilling areas. The simulation was carried out in NS-3/Aquasim-NG and ascertained that a layered topology of fixed position nodes with Depth Based Routing (DBR) would be optimal for time critical scenarios achieving the best time between sink and source and therefore the best option for a quick response to a hazard when compared to Hop-to-Hop Vector Based Forward (HH-VBF).