Uncrewed and Under the Radar: How AUVs Transform Drug Smuggling

Semi-submersible vessels, often referred to as ‘narcosubmarines’, have become a convenient and effective means for Latin American transnational criminal networks to transport narcotics such as cocaine to international markets. In July, the Colombian Navy reported that 10 semi-submersibles had been detected across Latin America in the first half of 2025 alone, though this likely represents only a small fraction of those in operation.

In recent years, these vessels have been detected increasingly further afield. In 2019, a semi-submersible from Brazil was discovered in Europe for the first time, proving their ability to complete transatlantic crossings. Since then, several have been intercepted off the Iberian Peninsula. In March, an empty vessel washed ashore in Sierra Leone, indicating the use of semi-submersibles to move drugs from South America to West Africa. They have even been detected in the middle of the Pacific Ocean, bound for markets in Australia and New Zealand, some 4,000 miles from their point of departure in Colombia.

The volume of drugs they carry also appears to be rising. In April, the Portuguese Navy intercepted a semisubmersible in the Atlantic Ocean carrying 6.5 tonnes of cocaine, the largest amount on record. Such seizures demonstrate how criminal networks continually innovate, adopting new technologies to increase range, carry greater loads and evade interdiction in pursuit of higher profits.

The latest technological development may be even more significant. On 2 July, the Colombian Navy captured an uncrewed semi-submersible off the coast of Tayrona National Park in Colombia’s Magdalena department. It was described by the Centro Internacional de Investigación y Análisis Contra Narcotráfico Marítimo (CMCON, International Centre for Research and Analysis Against Maritime Drug Trafficking) as an Autonomous Underwater Vehicle (AUV) and is the most advanced autonomous prototype of this nature discovered to date. The vessel was empty, indicating that it was likely undergoing a final test phase before being used to transport drugs.

The emergence of uncrewed semi-submersibles carries major implications for counternarcotics strategies centred on interdiction and deterrence, particularly as tensions ramp up in the Caribbean Sea.

The Evolution of Semi-Submersible Technology

In the 1980s, as authorities intensified interdiction of ‘go fast’ boats – then the principal means of transporting illicit drugs from South America to the US – drug trafficking groups began to develop semi-submersible vessels. The Colombian Navy seized the first semi-submersible in 1993. Since then, their capabilities have evolved significantly as criminal networks have sought to perfect the technology through experimentation and innovation. This evolution appears driven by two main strategic aims: transporting larger quantities of drugs and reducing the likelihood of detection by law enforcement.

Operating with most of their structure below the surface, semi-submersibles have significantly reduced their physical, thermal and acoustic signature. For added camouflage, semi-submersibles are often painted the same colour as the waters where they navigate. These features make them difficult to detect through aerial or maritime surveillance, making them one of the preferred transport modalities for drug traffickers.

Between 2011 and 2021, CMCON reported that drug trafficking groups had innovated in various ways, such as by using diesel engines to increase speeds, coating exhaust pipes with asbestos to reduce detection by thermal imaging cameras, and experimenting with different materials, such as steel, wood, carbon fibre and fiberglass to improve semi-submersible design. In 2017, Colombian authorities seized a semi-submersible equipped with a battery propulsion system that was capable of being fully submerged.

Another major breakthrough in recent years has been increasing the level of autonomy of these vessels. These uncrewed semi-submersibles are equipped with electronic devices and propulsion and navigation systems that allow them to be operated and piloted remotely or tasked to autonomously follow precise pre-programmed trajectories.

Prior to the 2025 interdiction, CMCON had recorded two cases of AUVs meant for these purposes. The first occurred on 27 November 2014, when the Colombian Navy’s detected an AUV at an abandoned camp in the Santa Bárbara estuary in Litoral del San Juan, Chocó department. The vessel was reportedly designed to be attached to another vessel close to shore and then released to navigate autonomously with its own propulsion. Later, on 4 June 2022, the Spanish authorities discovered three drone-like remotely operated semi-submersibles under construction near the port city Cádiz in Spain. These vessels were intended to move drugs across the Strait of Gibraltar and were equipped with GPS navigation systems and were capable of remote operation or monitoring from anywhere with internet access.

As a development from these earlier cases, the AUV detected in Colombia on 2 July 2025 was the largest and most technologically advanced iteration to date, and the first captured at sea. It was equipped with a GPS device, a satellite system with two Starlink antennas and two surveillance cameras. CMCON estimated its range to be approximately 500-800 nautical miles – capable of reaching the farthest shores of Central America – with the capacity to transport an estimated 1,500 kg of drugs. This marked a substantial improvement on previous models, which had a maximum range of just 50 km and capacity to transport up to 200 kg of drugs. Taken together, these successive seizures suggest that criminal networks have steadily refined AUV design and performance over time.

AUVs: A Cost-Benefit Analysis

AUVs are not without disadvantages. Without a crew, any technical malfunction at sea poses a major logistical challenge and risks the loss of valuable cargo. The fact that recent prototypes have been tested without drugs onboard suggests that organised crime groups are aware of these risks.

AUVs are also expensive to manufacture. A crewed semi-submersible reportedly costs about $1 million to construct, though this can be reduced to about $50,000 or $100,000 using 3D printing and lighter materials such as fibreglass and carbon fibre. While AUVs share the same basic design, structure and propulsion systems, they require additional components for automation and/or remote control. However, satellite and communication technologies are now widely accessible. For comparison, Tesla vehicles equipped with Starlink antennas and other automated equipment range in price from about $62,000 to $76,000, including engine and bodywork. On that basis, CMCON estimates that installing the necessary remote-control and automation equipment to a AUV would not exceed $50,000.

The strategic benefits of AUVs appear to outweigh the costs. Uncrewed design allows criminal networks to maximise cargo capacity by using the space normally allocated to crew for storing narcotics. CMCON notes that semi-submersibles typically require three crew members to sustain multi-day voyages. Going by the average adult male weight of 80kg, this equates to roughly 240 kg of weight that can be replaced by drugs. Considering the additional extra space saved from storing food and water, this could be even higher. Using CMCON’s 2024 estimate of a $30,000 wholesale price per kilogram of cocaine in the US, this additional capacity could yield an extra $7 million in profit per shipment. For markets in Australia and New Zealand where cocaine prices are three-to-six times higher, the added profit could be exponentially greater, making the extra cost of AUV construction negligible by comparison.

Another benefit is that without a crew onboard, AUVs allow drug trafficking groups to operate with greater secrecy. This removes the need to recruit reliable personnel and lowers the risk of information leakage, as fewer people are involved in drug trafficking operations. If an AUV is intercepted, there are no witnesses to reveal the vessel’s origin, destination, or the identities of those involved.

Recent developments further underscore the strategic appeal of uncrewed vessels. In a major escalation in the Caribbean Sea, US strikes between 2 September and 2 November 2025 – ordered by President Donald Trump against alleged drug trafficking vessels from Venezuela – reportedly killed at least 64 people. One of the strikes targeted a semi-submersible, killing two individuals. These actions likely aim to deter crews from navigating high-risk routes, due to the threat of being targeted in a lethal strike. Experts have questioned this supposed deterrent effect, noting that crew members already face the risk of arrest or death at sea. AUVs further undermine the argument for deterrence, as criminal networks can move drugs along high-risk routes without endangering human life.

Implications for Counternarcotics Efforts

AUVs clearly demonstrate the capacity of drug trafficking groups to innovate and adapt. Global satellite coverage and widespread availability of remote-control equipment provide well-resourced groups with the tools to experiment with new technologies and more effectively achieve their objectives, while staying ahead of enforcement agencies. These systems allow vessels to be operated from anywhere in the world, enabling the transport of greater volumes of drugs with a low likelihood of detection and minimal risk of information compromise if intercepted.

While the AUV captured by the Colombian Navy in July 2025 had a limited range – sufficient only to reach Central America – it is likely only a matter of time before they develop longer-range autonomous capability. Furthermore, the absence of interceptions involving drug-laden AUVs does not imply they are not already in use. Given the inherent challenges of detecting these vessels, it is plausible that they are already operating regularly.

In 2021, the US formally recognised AUVs as an emerging threat. US Coast Guard Commander Mark Barney observed that ‘though smugglers might still find existing trafficking methods superior to uncrewed systems, the Coast Guard must be prepared to counter the technology with creative solutions’. Indeed, traditional counternarcotics strategies reliant on interdiction, deterrence and intelligence derived from captured crew, may prove increasingly ineffective. AUVs reduce opportunities for detection, eliminate the deterrent effect associated with arrest or lethal force, and deprive authorities of valuable intelligence gathered from detained personnel.

This technological evolution underscores the urgent need for law enforcement agencies to adapt. Responding effectively will require not only innovative operational strategies but also accelerated investment in technological detection and interdiction capabilities and stronger international cooperation.

© RUSI, 2025.

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