In one run across the Straits of Gibraltar the subs would have been capable of smuggling more than 1,000 kilos (2,200 pounds) of cocaine from North Africa to Europe.
The gang could also have been acting as tech providers for other crime groups around the world, said police.
Officers also seized 10 vehicles, some of them reportedly hollowed out with secret compartments for trafficking on land.
They said it was the first time they had ever seized drone submarines, also known as unmanned underwater vehicles (UUVs), in Spain.
The Spanish authorities suspect that the gang used UUVs โcapable of bearing large loadsโ to transport drugs intended for distribution by other criminal groups.
The police said three UUVs were about to be delivered to a French criminal organization to โtransport significant amounts of cocaineโ, adding that the gang also had known customers in Denmark, Italy, and Spain.
The police said: โThese devices could allow drug traffickers to transport large quantities of narcotics remotely across the Strait of Gibraltar.โ
Each UUV had up to 12 motors and a maximum range of around 30 kilometers (18 miles), more than enough for the 15-kilometer (9-mile) crossing from Morocco to Spain.
Spanish national police have dismantled a gang developing underwater drones to traffic drug through Gibraltar Strait, July 2022. (Zenger)
Meanwhile, the six โunmanned semi-submersible vesselsโ could each carry up to 200 kilograms (440 pounds) of drugs, according to the police.
The Spanish authorities seized eight kilograms (17.6 pounds) of cannabis, 145 kilograms (320 pounds) of hashish and 157,370 euros ($162,335) in cash.
They also confiscated 10 vehicles, and the six underwater drones during eight raids across Spain.
The countryโs close proximity to Morocco โ a major hashish producer โ and its close ties with cocaine-producing former colonies in Latin America have made the country a key entry point for drugs bound for Europe.
Six of the eight suspects have been remanded in custody as the investigation continues.
For 90 years, the MSR has been more than a newspaperโitโs been a trusted voice for Black stories, struggles, and triumphs.
Your support today ensures that our legacy of empowerment and truth continues for the next generation. Together, we can keep our stories alive.
Support us as we support the community
Make a contribution to support community journalism today. All levels of support are greatly needed and appreciated.
We also welcome support in the form of checks to the MSR office at 3744 4th Avenue South, Minneapolis, 55409. The MSR is a for-profit business. Your support is not tax-deductible.
Stay in the know. Sign up for our newsletter!
Get your daily dose of community news, info, events, exclusive deals and more!