Like Hollander stated above, the Dutch organized crime networks ("penoze") are the traditional kind of organized crime in the Netherlands and are the most established. This mostly concerns high level Dutch criminals from working class towns surrounding big cities like Amsterdam, Rotterdam (a lot of them live in Schiedam these days),...trailer parks/camp sites ("woonwagenkampen") in especially North Brabant but also in South Limburg, South Holland (mostly around The Hague) and Drenthe. When it comes to the North Brabant networks plenty of high level criminals are not exclusively from the camp sites and also come from working class towns like St. Willebrord or from border towns in the Flemish Campines region.

The activities of the traditional Dutch networks depends on the region. Networks from North Brabant and South Limburg focus a lot on the production of and international trade in synthetic drugs. They're involved in importing cocaine and hashish (especially from Lebanon and Pakistan) as well, but the trade in synthetic drugs is their main bread and butter. Their turnover is enormous.
Networks from Rotterdam/Schiedam, The Hague region and Drenthe are mostly involved in the international cocaine and hashish trade.
The traditional Amsterdam area networks these days are mostly involved in the hashish trade and in extortative real estate deals; they mostly infiltrative the activities of shady realtors, contractors and bankers and squeeze them out.

Moroccans are the biggest minority group in the Netherlands and when it comes to the cocaine trade they have taken up a very important position. A lot of the retail trade in cocaine in big cities like Amsterdam, Utrecht and Rotterdam, but also in smaller cities in South Limburg is monopolized by Moroccan criminal families.
Whereas the trade in Lebanese and Pakistani hashish is largely the business of traditional Dutch networks, the importation and trade in Moroccan hashish is a mostly Moroccan affair. Most Dutch Moroccans have family members in the Rif in North Morocco and criminals use their family connections to set up these trafficking networks.
Their large scale involvement in the cocaine trade has made them a huge target for law enforcement and the police is coming down on the quite hard.

Gangs with origins in Suriname and Curaçao are also involved in the smuggling of cocaine. At the moment they're not as big time as the Moroccan groups (who import tons), but in their respective areas these gangs have the retail drug game on lock and they're highly territorial. It's not uncommon for them to fly in killers from the rainforest region in Suriname or from Curaçao. Sometimes Surinamese and Curaçaoan criminals also work in cahoots with Moroccan or Dutch criminals in the cocaine trade or do murder-for-hire jobs for them.

Outlaw motorcycle groups like Hells Angels (traditionally Dutch working class guys) or Satudarah (a one percenter composed of guys from Moluccan origin and Dutch working class guys) were traditionally highly active, but the government has forbidden them these days. They're still active in a more under-the-radar kind of way.

The strongest "transnational" organized crime groups in the Netherlands are traditionally the groups from Turkey, the Balkans and from Lithuania.

The Turkish underworld is extremely active in the heroin trade in the Netherlands, but they also dabble in cocaine and other stuff. It most concerns well known criminal organizations based in the Black Sea region of Turkey and East/Southeast Anatolia (mostly of Kurdish origin). Networks consisting of Netherlands-born Turkish criminals also exist of course and often cooperate with the networks based in Turkey.

Serbian/Montenegrin and Bosnian organized crime used to have a powerful base in the Netherlands as well, but mostly operate low-key these days.

"Russian" OC in the Netherlands are actually mostly Lithuanian networks that are active in car theft rings and chop shops, arms trafficking and smuggling contraband tobacco, fuel and substances used for the production of synthetic drugs.

There are other transnational groups active, but they're less established. Albanian networks in the Netherlands are not as entrenched as their counterparts in Belgium or Germany. Nigerian groups deal drugs, but not on a major scale. Chinese Triad activity is very low-key these days. Italian organized crime mostly launders money in the Netherlands. Criminals from the UK and Ireland often flee to the Netherlands, but don't really conduct any local territorial operations.