SSC Pacific Marine Mammal Program
Fleet Systems

In the Fleet's operational Marine Mammal Systems (MMS), the Navy uses dolphins and sea lions to find and mark the location of underwater objects. Dolphins are essential because their exceptional biological sonar is unmatched by hardware sonars in detecting objects in the water column and on the sea floor. Sea lions are used because they have very sensitive underwater directional hearing and exceptional vision in low light conditions. Both of these marine mammal species are trainable for tasks and are capable of repetitive deep diving.

Some of the objects the animals find are expensive to replace. Others could present a danger to Navy personnel and vessels. The dolphins and sea lions work under the care and close supervision of their handlers and are generally trained for a particular operational capability called a "system." (The term "system" is engineering jargon for a collection of personnel, equipment, operations processes, logistics procedures, and documentation that come together to perform a specific job.) However, animals may be crossed-trained for more than one system to better serve the needs of the Fleet. The term "mark" (MK for short) is military jargon for a type of thing within a category. There are 5 marine mammal systems called MK 4, MK 5, MK 6, MK 7, and MK 8. MK 4, MK 7, and MK 8 use dolphins, MK 5, which uses sea lions, and MK 6 uses both sea lions and dolphins. These human/animal teams can be deployed within 72 hours of notice and can be rapidly transported by ship, aircraft, helicopter, and land vehicles to potential regional conflict or staging areas all over the world. They regularly participate in major Fleet exercises. These animals are released almost daily untethered into the open ocean, and since the program began, only a few animals have not returned. Shipboard inflatable pools house bottlenose dolphins on fleet exercises and deploymentsA rainbow on a rainy day during a fleet exerciseA C-17, part of the Air Lift Command, sits poised on the runway while MMS are being loaded for an exercise

All Fleet systems are assigned to the Explosive Ordnance Disposal Group ONE (EODGRU ONE), where the mine hunting systems (MK 4, MK 7, and MK 8 MMS) are assigned to Explosive Ordnance Disposal Unit Mobile Unit (EODMU ONE). MK 5 is assigned to SSC Pacific and MK 6 is assigned to Navy Explosive Ordnance Disposal Mobile Unit THREE (EODMU THREE). SSC Pacific supports these Fleet systems with replenishment marine mammals, hardware, training, personnel, and documentation.

Mine Hunting Systems

Enemy sea mines have been responsible for 14 of the 19 Navy ships destroyed or damaged since 1950. That is why the Navy created the mine hunting systems. The mine detection systems are MK 4, MK 7, and MK 8 MMS. In the operation of these systems, a dolphin waits to receive a cue from its handler before it begins to search a specific area using its biological sonar called echolocation. When a dolphin echolocates, it emits a series of clicks that bounce off an object and return to the dolphin, allowing a dolphin to construct a mental image of the object. The dolphin reports back to its handler, giving one response if a target object is detected and a different response if no target object is detected. If a mine-like target is detected, the handler sends the dolphin to mark the location of the object so it can be avoided by Navy vessels or dealt with by Navy divers.

MK4 Marine Mammal System

A MK 4 dolphin attaches a marker to a tethered mine simulatorThe MK 4 MMS uses dolphins for detecting and/or marking the location of sea mines that are tethered off the ocean bottom. These deep-water mines are easy targets for the dolphin's highly effective echolocation. The MK 4 MMS offers reliable and effective mine detection, classification, and marking capabilities in areas that are highly cluttered or where rough seabed, high marine growth, and other complex acoustic conditions hamper the performance of Navy hardware systems.  

MK7 Marine Mammal System

In the MK 7 MMS, dolphins are trained to detect and/or mark the location of mines sitting on the ocean bottom or buried in sediment. The dolphins are sent out after the first troops have gone into the area. They help to clear a wider path of safety for additional troops and equipment.

A dolphin works in the open oceanAnother MK 7 MMS about to place a marker.MK 7 crew deploys a temporary enclosure to house bottlenose dolphins

MK 7 crew push their dive boat off a well deck while transporting a bottlenose dolphinA MK 7 mammal handler sprays water on a bottlenose dolphin before transporting it in the well deckA MK 7 mammal handler brushes the teeth of a bottlenose dolphin in the well deck aboard the USS Gunston Hall (LSD 44) operating

MK8 Marine Mammal System

MK 8 MMS is a human/dolphin team that allows troops to quickly identify safe corridors for the initial landing of troops ashore. MK 8 MMS operates with a low profile in very shallow water.

A MK 8 dolphin marking a practice targetAnother successful markStaff Sgt. Justin Roberts escorts a bottlenose dolphin in a rigid hull inflatable boat


A bottlenose dolphin leaps out of the water while trainingA bottlenose dolphin is beached up on a transporter mat before going out on a training missionThe Honorable Richard H. Jones, U.S. Ambassador to the State of Kuwait, visits the newest U.S. citizens at Camp Patriot, Kuwait.


Iraqi mines confiscated during mine sweeping and interdiction operations sit in a warehouse at the port of Umm Qasr, Iraq.

Force Protection

MK 6 dolphin marking a diverWhile dogs work as effective sentries on land, dolphins and sea lions cannot be outmatched as sentries in the water. In the MK 6 MMS, dolphins and sea lions effectively protect piers, ships, harbors, and anchorages against unauthorized swimmers, SCUBA divers, closed-circuit divers, and swimmer delivery vehicles.

MK 6 MMS was first operationally deployed with dolphins during the Vietnam War from 1971 to 1972 and Bahrain from 1986 to 1987.

MK 6 has now been expanded to include specially trained sea lions to locate water-borne intruders and suspicious objects near piers and ships that pose a possible threat to military forces in the area. They have been shown to be effective under and around ships, piers, and in open water.

The sea lions were deployed to Bahrain as part of the effort to support missions under Operation Enduring Freedom.

Sea lions are used to patrol in and around piers, pilings, and other tight spaces.Pouring some water over the sea lion keeps him wet and cool.A 375-pound California sea lion on patrol.


A MK 6 sea lion patrolling the harbor.A sea lion leaps back into the boat after a harbor patrol missionSea lions are effective sentries in harbors and other high-clutter areas.

Workers look on while a On patrolSnack time for Zak

A sea lion taking a breath Stay!

All MK 6 sea lion photos courtesy Navy NewsStand. Search for 'sea lion'.

Object Recovery

The Navy uses hardware and unarmed instrumented test equipment that may be launched from ships or dropped from planes into the ocean. Traditionally, these items were recovered by human divers. However, humans are restricted to short periods of working time on the bottom and can also be hampered by poor visibility, currents, and the requirement for surface support. To meet this need, the Navy developed the MK 5 "QuickFind" Marine Mammal System (MMS).


An early image of MK 5The MK 5 "QuickFind" system first demonstrated its capabilities when it recovered an ASROC (Anti Submarine Rocket) MK 17 from 180 feet of water in November of 1970. The MK 5 MMS became operational in 1975 and uses California sea lions to locate and attach recovery hardware to underwater objects such as practice mines. Some of these mines are equipped with a device called a pinger that sends out a tone to help the sea lion locate them. For this, the sea lion may have to dive to depths of 500 feet or more. The QuickFind system consists of a small rubber boat, a sea lion, and two or three handlers. When the boat arrives at the recovery site, the sea lion is sent over the side and given a bite plate to which an attachment device is mounted. The sea lion locates the object by using its exceptional low light vision and directional hearing to locate the undersea object. A strong line tied to the bite plate is payed out from the boat as the sea lion swims down and attaches the device. To be sure the connection is complete, the sea lion tests it by pulling back on the bite plate a few times. The sea lion then releases the bite plate and returns to the boat for a well-deserved reward of fish while the recovery vessel pulls the object to the surface.

The MK 5 "QuickFind" system provides an inexpensive method to recover submerged objects. Cost analyses have shown that this system is much less expensive for recovery than the use of dive teams or remotely operated vehicles (ROV). The sea lions' natural swimming ability makes it ideal for working in this environment and they are not hampered by decompression times. Their speed and agility allow them to recover objects much quicker than the mechanical options. The MK 5 MMS has also located submerged vehicles in a lake and had the opportunity to recover victims (dummies) in a simulated airplane crash.

As of 1 October 2005, SSC Pacific has taken over the daily operations of MK 5 after many years of being part of EODMU THREE.

Requesting Services

The use of the MK 5 "QuickFind" MMS to recover objects is not limited to Navy assets. The system is available for tasking from any branch of the armed forces or RDT&E labs. In most cases the cost for employing MK 5 is limited to travel and per diem expenses. To request the recovery services of the MK 5 "QuickFind" MMS please download and fill out the following request form:

Email the completed form or any other inquiries to

Sea lions can also bring down a tethered camera so operators at the surface can assess the situation.MK 5 locating a practice targetMK 5 sea lion finding a drone for recovery


Another successful missionA MK 5 sea lion is about to attach the recovery hardware to a simulator.

Fleet Support

Animal Production

The Spares Program provides back-up animals for all the systems in the Fleet to help maintain uninterrupted mission readiness. Not only are the spares animals trained the advanced skills they will need to replace an animal that has been taken out of the Fleet, they are also on call, ready to step in at any time to fill in for another animal that is temporarily unavailable or to fill the needs of an expanded mission. It is in the Spares program that new technologies and training techniques are innovated and validated to ensure that the Marine Mammal Program always maintains the highest caliber product.

Technical Representative

Marine mammal handlers in the Fleet participate in a course of study that includes marine mammal husbandry, training, and systems operations. Each Fleet system is also supported by an experienced civilian marine mammal trainer called a technical representative. Technical representatives are essential personnel and an integral part of the Fleet systems. They provide support and expertise during daily operations, as well as deploying with the systems on military exercises and operations. They also act as a liaison between the Fleet and the NMMP to ensure that the Fleet's needs are being met and that the highest level of animal care is maintained.

Systems Engineering

An expert team of talented engineers maintains continual vigilance on hardware to ensure the efficiency and safety of current hardware and enhance the operational capabilities of the system through new designs of existing equipment and the development of new hardware.

Maintenance Depot

The Marine Mammal Program has a materials and equipment storage and maintenance facility known as the Depot to provide Fleet equipment needed for operation of marine mammal systems. The personnel at the Depot have years of experience with the program. They provide an efficient means of helping the Fleet to prepare for an exercise or operation and ensure that all the equipment is properly maintained to enhance mission readiness.


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Updated: 8/29/2011 11:45 AM EST   Published (1.0)