The use of sensors for undersea warfare (USW) missions involves a wide spectrum of approaches. Among the many related research and development thrusts is a healthy focus on computer automation and flexible sensor positioning by low cost semi-autonomous platforms. Automation is being applied to organic sensors on large capital ships as well as distributed sensors detached from a central command center for the purposes of increasing area search rate, managing workload, and reducing cost. Particular capabilities are driven by mission-specific considerations such as large area or barrier search in deep water, shallow littorals, or riverine locations. For example, automation incorporated in undersea sensors on mobile unmanned vehicles will likely be different than approaches implemented on larger ships. Likewise, leave behind sensors on the surface or bottom will provide yet different performance attributes. Autonomous platforms including the unmanned undersea vehicle (UUV), unmanned surface vehicle (USV) and unmanned air vehicles (UAV) will host sensors that play a key role. The resulting landscape includes a fairly intricate set of sensor types, platforms, and operational methods. An overview of selected unmanned and/or unattended naval undersea sensor technologies is discussed, along with some of the inherent capabilities that make them advantageous to specific USW missions. One example of cost savings achievable through extensive use of automation is provided to illustrate potential ancillary benefits. The primary technical challenges that need to be overcome before these sensors can reach their desired operational capability are also discussed.