While several Belgian bands on this year’s bill represent the future of the scene, Poseydon proudly carry its history. Originally formed back in 1992, the East Flanders veterans have spent decades flying the flag for old-school death and thrash metal, drawing inspiration from legends like Slayer, Sepultura and Testament while forging an identity of their own through powerful grooves, soaring solos and themes rooted in mythology and warfare.

After reuniting in 2006, the band have continued to build an impressive catalogue, most recently adding Time Is A River And The Waters Are Red to their discography earlier this year. Despite their long-standing status within the Belgian underground, this summer finally sees Poseydon make their Alcatraz debut—a milestone that’s arguably long overdue.

For anyone who still believes there’s nothing quite like honest, no-nonsense old-school metal played with conviction, Poseydon are a band you won’t want to miss when they open La Morgue on Saturday.

No Belgian band on Saturday combines outrageous humour with uncompromising extremity quite like Brutal Sphincter.

The five-piece have built an international reputation through their unmistakable blend of goregrind, brutal death metal and what they proudly describe as “POOlitical” humour. Behind the ridiculous song titles and over-the-top stage antics, however, lies a band that isn’t afraid to tackle real-world issues through satire, all while delivering absurdly tight musicianship and enough blast beats to satisfy even the most extreme metal fan. Their reputation has carried them to some of Europe’s biggest festivals, including Hellfest, Summer Breeze and, of course, Alcatraz. We also had the pleasure of sitting down with the band at Tolminator last year, where it quickly became clear that the same tongue-in-cheek attitude they display on stage carries over into conversation as well.

Whether you’re already a devoted member of the Sphinct-Earth Society or simply curious to experience one of Belgium’s most entertaining live bands, don’t expect to leave without a smile on your face.

One of Saturday’s Alcatraz debuts comes courtesy of Kortrijk’s own Divided, making this something of a home game for the band.

Since forming in 2020, the quartet have quickly built a reputation with an emotionally charged blend of post-metal, sludge and hardcore, balancing crushing heaviness with moments of atmosphere and melody. Their debut album Light Will Shine, released through Dunk! Records in 2024, firmly established them as one of the more exciting names emerging from Belgium’s post-metal scene, while tours alongside bands like Brutus, Wiegedood and LLNN have only helped spread the word beyond our borders.

Playing Alcatraz for the first time is another significant step forward, and there’s something fitting about making that debut so close to home. If you’re looking for a set that favours emotion and atmosphere just as much as sheer heaviness, Divided are well worth making time for.

For well over fifteen years, Your Highness have been one of the pillars of Belgium’s sludge scene, proving that crushing heaviness and irresistible grooves can go hand in hand.

The Antwerp band have continuously refined their sound since first emerging in 2009, blending massive down-tuned riffs with bluesy undertones, Southern rock swagger and an unmistakable sense of groove. Albums like City in Ruins and, more recently, Under The Weight have only strengthened their reputation as one of the country’s premier sludge outfits. Their live résumé speaks for itself, with appearances at festivals such as Roadburn, Desertfest, Graspop and Pukkelpop, while their DIY mentality remains firmly intact. They’re the kind of band that can flatten you with sheer heaviness one moment before locking into a groove that has the entire crowd nodding along the next.

If your ideal festival set involves thick riffs, massive grooves and a healthy amount of headbanging, make sure Your Highness are part of your Saturday.

Few bands embody Alcatraz‘s commitment to supporting homegrown talent quite like Mantah.

Over the past few years, we’ve watched the outfit steadily climb the festival ladder. It all started with a memorable performance on the intimate La Morgue stage that quickly became one of the talking points of the weekend. The following year, they earned a promotion to one of the larger stages, and now they return even higher up the bill once again. It’s the kind of progression that perfectly illustrates how Alcatraz continues to invest in promising Belgian bands instead of simply giving them a single opportunity.

Musically, Mantah blend modern metalcore with flashes of nu metal and electronics, creating an energetic, contemporary sound that’s perfectly matched by their explosive live performances. Add the recent release of another new album and a summer that has already seen them conquer major festival stages, creating a whole lot of buzz after they got to open the main stage at Belgium’s biggest metalfest Graspop, and it’s clear they’re continuing their upward trajectory.

If you’ve followed their rise over the past few years, this performance will feel like another well-earned milestone. If you haven’t, there’s every chance you’ll leave wondering why you hadn’t caught them sooner.

If controlled chaos had a soundtrack, there’s a good chance Ronker would be playing it. The Denderleeuw outfit have been on a seemingly unstoppable rise since forming in 2020, carving out their own corner of the heavy music landscape with what they proudly call “speednoise.” Blending hardcore, noise rock, punk and alternative metal into an explosive sonic assault, Ronker have become one of Belgium’s most talked-about young live bands, earning praise through sheer intensity rather than gimmicks.

That reputation is taking them far beyond Belgium this year, with appearances at festivals including ArcTanGent, Dynamo Metalfest, Pukkelpop and of course, their very first Alcatraz. Their latest album, Respect The Hustle, I Won’t Be Your Dog Forever, only reinforces the feeling that this is a band rapidly outgrowing the underground while refusing to smooth off any of its rough edges.

If you like your live shows sweaty, unpredictable and bursting with energy, Ronker should be near the top of your Saturday schedule.

By now, Psychonaut have grown into one of Belgium’s most respected heavy music exports. The Mechelen trio have spent more than a decade crafting expansive compositions that effortlessly move between crushing sludge, progressive metal and psychedelic soundscapes, all tied together by themes exploring consciousness, spirituality and the human condition.

Their latest album World Maker saw the band reach perhaps their most personal point yet, proving once again why Pelagic Records continues to be such a fitting home for their music. On stage, those songs come to life through an immersive audiovisual experience that has earned them invitations to festivals such as Roadburn and Soulcrusher, while steadily building a reputation far beyond Belgium’s borders.

Psychonaut have become one of those Belgian bands that seem destined for bigger and bigger stages. If you’ve somehow never experienced them live before, Saturday offers the perfect opportunity to find out why they’re held in such high regard.