Guardia Civil officers arrested 14 members of a drug trafficking gang that operated from properties in Palmones.
Officers raided several houses in La Linea and Algeciras, seizing four large rigid-hulled inflatable boats, two smaller vessels, a jet ski, six luxury vehicles and 520 kilos of cannabis resin.
A Taser gun and 7,000 euros in cash were also seized.
The gang, all Spanish, had initially shipped drugs through the Guadarranque river but when this was closed off by authorities with a barrier, they switched to Palmones.
The gang tried on several occasions to ship drugs via the Palmones river but were intercepted by the Guardia Civil on at least three occasions.