EXTREMA RATIO ULTRAMARINE FIXED BLADE KNIFE WITH SHEATH
The ULTRAMARINE is an amphibious knife, carried around from underwater operation equipment (diving suit) to ground operation equipment (tactical vest).
EXTREMA RATIO ULTRAMARINE FIXED-BLADE KNIFE: YOUR ULTIMATE AMPHIBIOUS COMPANION
Experience a new level of tactical versatility with the Extrema Ratio Ultramarine. Engineered in Italy for both underwater missions and ground operations, this knife adapts seamlessly to every environment you encounter. Crafted from BöHLER N690 stainless steel and heat-treated to a rock-solid 58 HRC, the 150 mm blade delivers razor-sharp performance and undeniable resilience, even in the most corrosive marine conditions.
Designed hand-in-hand with elite military divers and special-ops teams, the Ultramarine comes with two specialized sheaths. Strap the lightweight ABS scuba sheath to your ankle or breathing apparatus for quick underwater access. Once you hit land, simply slide the knife out, stow it in the MOLLE-compatible tactical vest sheath, and keep moving without missing a beat. No extra tools, no wasted time—just instant readiness whenever duty calls.
Every inch of the Ultramarine reflects Extrema Ratio’s relentless commitment to quality. The blade’s flat grind and precision-engineered serration deliver clean, controlled cuts through rope, webbing, and fibrous materials. The ergonomic nylon handle with textured inlays provides a secure, fatigue-free grip whether you’re underwater, in humid jungles, or under the blazing sun. An integral guard and reinforced tang maximize strength, turning this knife into a true multi-tool for survival, combat, and emergency extraction.
Since 1997, Extrema Ratio has blended cutting-edge CAD/CAM design with old-world Italian craftsmanship. Each model is meticulously prototyped, field-tested by professionals, and hand-finished by master craftsmen in Prato. The result? A knife that stands up to the harshest mil-spec demands while remaining a reliable everyday partner for search and rescue teams, law enforcement, and outdoor enthusiasts alike.
Whether you’re a professional diver, a tactical operator, or an adventure seeker, the Ultramarine is engineered to exceed expectations. Lightweight yet robust, it’s ready for deep-sea dives one moment, rooftop extractions the next. Trust in a legacy of innovation and build your kit around a tool that’s as fearless and adaptable as you are.
KEY FEATURES AND SPECIFICATIONS
• Amphibious Design: Seamlessly transitions from underwater missions to ground operations
• Dual Sheath System: Removable scuba sheath with ankle and belt-clip options; MOLLE-compatible tactical sheath
• Blade Material: Premium BöHLER N690 stainless steel—corrosion-resistant to excel in saltwater
• Hardness: 58 HRC for long-lasting edge retention and toughness
• Blade Profile: 150 mm flat grind with 40 mm saw-tooth serration for versatile cutting
• Overall Length: 298 mm (11.7 in) for balanced control and reach
• Blade Thickness: 6.3 mm (0.25 in) for maximum durability under stress
• Handle: Ergonomic nylon with textured grip for secure handling in wet and dry conditions
• Full Tang Construction: Reinforced strength and impact resistance
• Finish: MIL-C-13924 burnishing for a matte, non-reflective surface
• Weight: 395 g (13.9 oz) for portability without compromising robustness
• Primary Uses: Field operations, underwater tasks, emergency tool, survival and combat
• Origin: Designed and handcrafted in Prato, Italy, by trusted military-grade cutlery experts
