Underwater Port Security System
- See UIS (disambiguation) and IAS (disambiguation) for other meanings of these initials.
- For other diver-detector sonars, see Category:Diver-detector sonars.
Underwater Port Security System (UPSS) was developed for the United States Coast Guard and the Maritime Safety and Security Teams (MSSTs) as an anti-frogman technique. It includes the Underwater Inspection System (UIS) and the Integrated Anti-Swimmer System (IAS). Recent developments in terrorism have highlighted the need for underwater anti-frogman security. The UPSS is made in the United States and is reported to be compact enough fit in a large suitcase.
Ship Protection System 
The Ship Protection System or SPS is a ship based underwater threat detection system manufactured by FarSounder, Inc. Based on FarSounder's 3D forward looking sonar, their SPS offers 360 degree coverage of underwater threats to vessels on anchor or at dock. This is a commercial product suitable for mega yachts.
Underwater Inspection System 
The Underwater Inspection System or UIS is a system manufactured by CodaOctopus and consists of the unique Echoscope Real Time 3D Sonar that is used to scan the underwater environment in zero visibility waters. The UIS system can be mounted on a small boat to scan harbor walls, piers, bridges for an underwater threat and can be used to complement long range diver detection systems by classifying the threat in 3D in real time. The same system can be mounted on remotely operated vehicles (ROVs) to create 3D ship hull scans detecting small mine size objects.
Integrated Anti-Swimmer System 
- SM2000 (Underwater Surveillance System), a search sonar made by Kongsberg Maritime.
- An underwater warning loudspeaker.
- An underwater shockwave emitter that can force divers to surface, or stun or kill them. The US Coast Guard calls it an "nonlethal interdiction acoustic impulse".
It can track underwater objects, similarly to an air traffic control radar. Like other systems, such as the Cerberus, it is semi-intelligent and can distinguish humans from marine animals, partly because of their different shapes and typical movements underwater. This is not impeded by darkness or fog or low underwater visibility, and is a great improvement on scanning the water surface by eye from above. Various test attempts by MSST divers to trick the system did not work.
In most cases the detected diver would be warned by the underwater loudspeaker; after that, the shockwave emitter would be fired once as a warning, before it is fired to stun or kill.
Other Anti-Swimmer-based systems that have been invented, instead of shock-waves, use sound-waves which 'disrupt' the diver causing sickness and disorientation. This technique is considered non-lethal and has been developed using an array of underwater speakers.
- http://www.military.com/NewsContent/0,13319,uscg1_031405.00.html Mission Detection: The Underwater Port Security System