The 'top secret' stealth boats designed for Navy SEALs that are regularly spotted on the Columbia river

For more than a decade there have been sightings of unusual high-speed watercraft patrolling up and down the Columbia River

The vessels belong to the Navy SEALs and are part of an ongoing project called Sealion

Despite being in existence for more than a decade, the project remains shrouded in mystery

The Navy's intention was to use the craft as a medium-range method of transporting SEALs without appearing on the enemy's radar

The original Sealion, cost $9 million and was delivered in 2003 when a demonstration is understood to have taken place

It isn't clear if Sealion ll has ever even become semi-operational, but the program remains active because new boats keep appearing on the river



For more than a decade there have been sightings of unusual high-speed watercraft patrolling up and down the Columbia River between Portland, Oregon and Vancouver in Canada.



The vessels belong to the Navy SEALs and are part of an ongoing project called Sealion, which stands for SEAL (Sea Air Land Commandos) Insertion, Observation and Neutralization.



Despite being in existence for more than a decade, the project remains shrouded in mystery, although over the years some information has been discovered.

For more than a decade there have been sightings of unusual high-speed watercraft on the Columbia River, the vessels belong to the Navy SEALs and are part of an ongoing project called Sealion

Sealion is an experiment between the US Navy's Surface Warfare Command and the Naval Special Warfare Command.



Launched in 2000, the brief was to develop a high-speed, low observable/low radar signature craft that could operate in the littorals i.e. the part of sea close to shore.

The Navy's intention was to use the craft as a medium-range method of transporting SEALs without appearing on the enemy's radar.



Sealion is operationally controlled by Naval Special Warfare Group (NSWG) 4 at Naval Amphibious Base Little Creek, Va, reports FoxtrotAlpha.



The Navy's intention was to use the craft as a medium-range method of transporting SEALs without being appearing on the enemy's radar

Launched in 2000, the Sealion brief was to develop a high-speed, low observable/low radar signature craft that could operate in the littorals i.e. the part of sea close to shore

‘The purpose of the project was to build a demonstration craft to explore the use of technology that may have future application in the Global War on Terrorism,’ said Capt. Evin H. Thompson, one-time commander of NSWG 4, speaking about the original version of the craft.



Known simply as Sealion, it measured 71 feet and required a crew of one or two sailors to operate. It was capable of 40 knots under normal conditions and no less than 30 knots in sea states as high as level five.



The original Sealion, cost $9 million and was delivered in 2003 when a demonstration is understood to have taken place.

However the boat was never put into production and instead the decision was taken to develop the slightly more advanced Sealion ll.

Sealion is operationally controlled by Naval Special Warfare Group (NSWG) 4 at Naval Amphibious Base Little Creek, Va,

A rear opening garage-like door would allow for deployment and recovery of these craft with relative ease and without compromising the boat's stealth capabilities for more than a short period of time

It appears to have been a refinement of the original design and is rumored to have offered an even lower radar cross section than its predecessor, but was also big enough to carry an unspecified number of SEALs and a modular mission payload.



It also required just a single crewman to operate.



The state-of-the-art electronics suite included a retractable FLIR turret, communications array and radar, along with a highly automated command and control system.



According to Thompson, NSWG 4 was looking at Sealion II as a potential platform for weapons systems and intelligence collection.



A rear opening garage-like door would allow for deployment and recovery of these craft with relative ease and without compromising the boat's stealth capabilities for more than a short period of time.

Despite being in existence for more than a decade, the Sealion project remains surrounded in mystery, although over the years some information has been disclosed

Another supposed benefit of the Sealion ll was that it could be used to sneak up on a moving target, such as a large ship.

Without showing up on its radar would clearly offer a huge advantage over boats normally used for missions which do not feature a high degree of 'low observable' technology.



It isn't clear if the Sealion ll has ever become even semi-operational within the Navy, but the program appears to remains active because new boats keep appearing on the Columbia year after year.



Even boaters who have spotted a Sealion visually as it is semi-submerged say that it does not show up on their commercial grade radars, which is at least some proof to the Sealion's cloaking capabilities.



Even boaters who have spotted a Sealion visually as it is semi-submerged say that it does not show up on their commercial grade radars, which is at least some proof to the Sealion's cloaking capabilities