Over 20 people were arrested during the raids carried out in several provinces in Andalusia, a spokesman for Spain's Guardia Civil police force said.
Several boats suspected of being used to ship hashish to Spain from Morocco were seized, mainly in the region bordering the Guadalquivir river, which is navigable from the Gulf of Cadiz to Seville, he added.
In a separate operation carried out on Tuesday, Spanish National Police arrested 15 people suspected of belonging to a group based in the southern city of La Linea de Concepcion that provided fuel and food to smugglers who use speedboats to move hashish from Morocco to Spain's southern coast.
La Linea, an underprivileged city with high unemployment at the edge of the Strait of Gibraltar which separates Andalusia from Africa by just 15 kilometres (nine miles), is the epicentre of the hashish trade.
It is part of the province of Cadiz, which accounted for over half of the 335 tonnes of hashish seized in Spain in 2017, according to the last available figures.
Police have increased their raids against suspected drug traffickers in the area recently because they “are collecting the fruits of investigations” they launched in some cases several years ago when gangs began operating in an increasingly brazen manner, said Ricardo Magaz, a criminologist at Spain's UNED university.
Traffickers bring consignments of drugs onto the beach in the area, often in broad daylight, and police and other authorities have been physically attacked, such as in February 2018 when members of a drug smuggling gang attacked a hospital in La Linea to free one of their members who was injured in a police chase.
Authorities also became alarmed by signs that local gangs were establishing links with foreign mafias and Madrid responded by sending police reinforcements to the region.
Earlier this month, the interior ministry announced it had ended an investigation it opened in 2016 by smashing a drug smuggling gang which included members of the Italy's 'Ndrangheta organised crime group.
Luxury cars, music videos
Two members of “Los Castanas”, thought to be the largest hashish smuggling ring in the Strait, were part of this gang.
The operation follows the arrest last year of two brothers who led “Los Castanas”.
These police operations have weakened the drug smuggling gangs and prompt some of them to betray each other, said Magaz.
The crackdown has been aided by carelessness on the part of the local traffickers, who often show off their new-found wealth by driving luxury cars or appearing in music videos.
But Mugaz warned that the authorities can't declare victory because as soon as a drug baron is arrested “there is a replacement, or a neighbouring clan or rival takes over his activities”.
Traffickers are now spread out throughout Andalusia rather then being concentrated in Cadiz province, a Civil Guard source said.
The pressure which police have put on traffickers in the La Linea and the surrounding area known as the Campo de Gibraltar “has caused criminal groups to try to leave the Campo de Gibraltar and associate themselves with organisations in other places,” the source added.