Katheryn Winnick’s portrayal of the fierce shieldmaiden Lagertha in the hit History Channel series Vikings (2013–2020) has cemented her as a fan favorite and a symbol of unyielding strength. From wielding axes in brutal battles to navigating the treacherous politics of Viking society, Winnick embodied the complexity of a warrior woman who was both passionate and profoundly human. Yet, behind the epic sword fights and dramatic betrayals, there was one scene that pushed the actress to her physical limits—not a gruesome execution or a heart-wrenching death, but a seemingly simple plunge into icy waters clad in heavy armor. In a candid revelation, Winnick shared how this underwater ordeal became her toughest challenge on set, offering a glimpse into the grueling realities of bringing Vikings to life.

Lagertha: A Role That Demanded Everything

Before diving into the depths (literally), it’s worth revisiting why Winnick’s Lagertha resonated so deeply. Based loosely on the legendary figure from Norse sagas, Lagertha was Ragnar Lothbrok’s first wife, a skilled fighter, and a leader in her own right. Winnick, a fourth-degree black belt in taekwondo and a trained martial artist, brought authenticity to the role with her athletic prowess and emotional depth. She trained rigorously, even purchasing a Viking costume before auditioning to immerse herself in the character.

Critics and fans alike praised her performance. Entertainment Weekly’s Darren Franich called Lagertha “a potent central figure,” highlighting arcs like cradling her dying grandchild or slaying a traitorous husband on their wedding night. Winnick herself was drawn to the character’s modernity amid ancient times: “She’s a very strong woman, and she’s definitely modern for her time,” she told Collider. But for all the empowerment, the role came with physical tolls that tested even her resilience.

The Scene: A Frozen Nightmare in Full Armor

The infamous scene in question? A swim in freezing waters while weighed down by pounds of armor. Far from the blood-soaked raids that defined Vikings, this moment captured the raw peril of Viking life—crossing treacherous fjords or seas under harsh Nordic conditions. Shot outdoors in Ireland’s unforgiving climate, the sequence demanded Winnick and her co-stars submerge themselves in near-freezing temperatures, their movements restricted by authentic leather and metal gear.

In an Instagram Live Q&A with fans, Winnick didn’t mince words: “Swimming in the freezing water with pounds of armor on.”
The conditions were so extreme that a medic was on standby, monitoring the cast for signs of hypothermia or shock. “Your body would literally be frozen,” she recounted to Metro UK.
The cold seeped into every fiber, turning a routine shoot into a survival test. Winnick, no stranger to action—having starred in films like The Art of the Steal and later Big Sky—admitted this topped even the most violent fight scenes.

The production’s commitment to realism amplified the hardship. Vikings was filmed in Ireland and Canada, where winter shoots meant battling rain, wind, and sub-zero temps. Armor, while visually stunning, added 20–30 pounds of dead weight, making each stroke a Herculean effort. Co-stars like Travis Fimmel (Ragnar) and Clive Standen (Rollo) faced similar rigors, but Winnick’s scene stood out for its isolation—combining immersion in water with the armor’s drag, all while maintaining the poise of a shieldmaiden.

Emotional and Physical Toll: More Than Just the Cold

Winnick’s struggle wasn’t solely physical; it mirrored the emotional layers of Lagertha’s journey. The character endured loss, betrayal, and reinvention, and Winnick channeled that vulnerability into her performance. Reflecting on the series’ end, she revealed in a 2025 Collider interview that she still can’t watch Lagertha’s death scene, five years later: “She still lives in a part of my heart.”
Directed by Ciarán Donnelly, that finale—where prophecy leads to her demise at Hvitserk’s hands—was emotionally brutal, shot amid inclement weather on one of the last days of production.

This underwater scene, though earlier in the series, foreshadowed such intensity. “We had a medic on set and he was checking us if we would go into shock,” Winnick shared, underscoring the production’s safety measures.
Her taekwondo background helped, but nothing prepared her for the armor’s chill against bare skin or the disorientation of cold water. It was a reminder that Vikings wasn’t just about glorifying warriors; it humanized their endurance against nature’s indifference.

Behind-the-Scenes: The Making of a Shieldmaiden

Winnick’s preparation for Vikings was as methodical as Lagertha’s strategies. Born in Etobicoke, Ontario, to Ukrainian immigrant parents, she spoke Ukrainian before English and earned her black belt at 13. By 21, she’d opened three taekwondo schools while studying kinesiology at York University. This discipline translated to set, where she trained with weapons and horses, ensuring every fight felt visceral.

The show’s creators, led by Michael Hirst, prioritized historical(ish) accuracy, consulting experts on Viking lore. Underwater scenes like this one drew from real sagas of sea voyages, but safety protocols were modern: heated tents, warm robes, and limited takes. Still, Winnick pushed boundaries, embodying the “potent central figure” fans adored. Her directorial debut in Season 6 further showcased her investment, helming an episode with the same grit.

Post-Vikings, Winnick’s career soared. She led Big Sky (2020–2023), produced via her company Kat Scratch Inc., and founded The Winnick Foundation for humanitarian aid to women and children. Yet, she credits Vikings with transforming her: “It was the role of a lifetime,” she said, even if it meant freezing for authenticity.

A Lasting Legacy: Strength Forged in Ice

Katheryn Winnick’s toughest Vikings scene—a submerged battle with hypothermia—encapsulates what made the series endure: unflinching realism amid mythic storytelling. It wasn’t the axes or ambushes that broke her, but the quiet terror of cold waters, a foe as timeless as the Vikings themselves. This revelation humanizes a star often seen as invincible, reminding us that true strength involves vulnerability.

As Vikings spin-offs like Vikings: Valhalla carry the torch, Winnick’s Lagertha remains iconic. Her story inspires not just actors facing harsh shoots, but anyone conquering personal “freezing waters.” In Winnick’s words, it’s about persisting: one stroke, one breath at a time. For that, Lagertha—and her portrayer—will forever be legends.