We are in a market that is almost completely saturated with ideas, where companies focus more on improving materials than on discovering new solutions. When it comes to fins, blade variety mainly depends on the different materials used, especially in the case of composites. However, there is something different—something created by C4: the UP Ghost, the first and only fin on the market with a transparent blade.

The concept of "transparency" has had a difficult history, tainted by an earlier model released some time ago by another company. Due to frequent breakages, that product contributed to a negative reputation, overshadowing the utility and uniqueness of transparent fins.

Now, the Lombard company has decided to turn past challenges into advantages, using them as a foundation for innovation. The first step was to dedicate a division of their team to the production and research of plastic injection-molded products. This led to the search for a high-performance material that was both strong and maintained its transparency.

The result was the discovery of a unique and specialized technopolymer, which costs three times more than any other plastic material used for blade production and required custom molds and specific molding techniques.

"The outcome is a blade that has passed the most rigorous breakage tests ever conducted—tests even carbon models aren’t subjected to," C4 explained. "One of the most challenging tests was an eight-month-long robotic pool cycle, which totaled an astonishing 1,411,200 cycles. And if that weren’t enough, our team of athletes worldwide continued testing the prototypes under real-world conditions, in both freshwater and saltwater environments."

In short, this is an incredibly durable blade that has never broken, even under extreme stress—such as impacts against rocks, as demonstrated by some team members on social media. It is undoubtedly an innovative product, 100% Made in Italy.

Now, let’s take a closer look. Removing the fins from their transparent packaging, we immediately notice the familiar pairing with the 250 foot pocket, a model we have tested and admired for its efficiency, design, and above all, comfort. The new Up Ghost blade is secured with two mini side rails and a hand-tightened screw-and-nut system. It is completely transparent, except for two opaque sections in the center resembling wings. This design prevents unwanted reflections, particularly when used in shallow water on sunny days.

At first glance, the structure is simple and minimalist, with only the small transparent water rails near the tip and two reinforcing ribs under the blade, which enhance resistance and motion transmission. But the real secret lies in the technopolymer used—a material that is extremely strong, flexible, and responsive, to the point that "its performance comes close to some carbon models," C4 emphasizes.

The new Up Ghost is available in a single Medium stiffness. Sizes range from 36/37 to 44/45, with a recommended retail price of €170.

At Sea

Having been part of the C4 team for years, it would be hypocritical not to acknowledge my active involvement in testing the various prototypes. However, I won’t hide the fact that throughout all tested models, the focus has always been on improvements and aesthetic upgrades, without ever encountering breakages or structural failures. It can therefore be said that this project was built on solid foundations, likely as a response to past issues experienced by other brands.

With this necessary preface out of the way, I must admit that after months of post-test silence, I was eager to finally see the finished product, which I would test and review for the magazine. I was curious about the suggested improvements and excited to see how impactful they would be, especially for someone like me who enjoys spearfishing in shallow waters. When I finally received the final model, what better opportunity to test it than a shore dive?

At this point, it almost feels redundant to emphasize the comfort of the 250 foot pockets, in this case in size 41/42. The 29-degree blade angle, combined with the 3-degree preformed foot pocket, allows for a relaxed ankle position, making finning easier.

The blade’s performance is truly exceptional. Despite the excess weight from the backplate, the fin holds up incredibly well under stress, allowing me to move efficiently on the surface and providing excellent propulsion when pushing off the bottom.

But let’s talk about its standout feature: transparency. It’s amusing, but I spend most of my time in shallow waters glancing over my shoulder, observing firsthand how the blade adapts to the different shades of the seabed. It blends seamlessly with seagrass, becomes a chameleon on the sand, and forms a collage of colors on rocky terrain. Initially, I thought the opaque sections might be a drawback, but they actually enhance the camouflage effect even further. They help minimize unwanted reflections from the sun, which would otherwise be amplified by the water’s transparency.

Removing the backplate, I venture toward some familiar rocky areas not far from shore. Even during the most demanding dives, the Ghost performs flawlessly. The official website classifies the blade as Medium stiffness, but it feels like it has a smooth, soft-like flex while still delivering all the propulsion and thrust of a Medium stiffness fin.

Diving around the 20-meter mark, the fin performs brilliantly. It provides excellent push-off from the bottom and maintains a good cruising speed relative to effort. I’d recommend it both to shallow-water hunters looking for the perfect balance between camouflage and performance and to those who dive deeper but don’t want to invest in high-end carbon fins.

On the way back, it’s time for the usual post-dive reflections. The day’s catches weren’t solely thanks to the fins, but it’s incredible how they enhanced my ability to blend in with the environment—despite their total length of about 90 cm. Visually, only the foot pocket remains noticeable, as the blade becomes practically invisible.

After several hours in the water, leg fatigue is almost nonexistent. The technopolymer used is truly impressive—it doesn’t make me miss carbon at all. Quite the feat for a "plastic" fin!

In short, the UP Ghost is a powerful, robust fin that has little to nothing in common with old transparent models.

Back on land, after removing my gear, I pack everything into my bag, ready to head home. While rinsing the fins, I notice a slight deformation toward the tip due to their time inside the bag. This is a characteristic of the material—it’s highly durable and resistant but also flexible and subject to slight bending. To prevent this, I recommend always storing them on a flat surface. However, if it happens, there’s no need to worry. Simply place the Ghost fins on a flat surface and apply weights in the opposite direction of the bend. After a few hours, they will return to their original shape.

Additionally, C4 includes a handy insert in the package that, when placed inside the foot pocket, allows you to hang the fins—eliminating the problem at its source.

Scores

Structure: 8.5 Simple and functional, allowing the fin to perform optimally in all situations.

Materials: 10 To erase the ghosts of the past, C4 had to push research at full speed to find the right material—one that combines elasticity, lightness, and above all, durability. And let’s not forget, it had to remain transparent. Judging by the results, they succeeded! We used it on multiple dives without encountering any issues.

Comfort: 9 The 250 foot pocket remains one of the best on the market. Combined with C4’s signature ergonomic angles, it delivers a pleasant fit without causing discomfort, even after prolonged use.

Performance: 9 We were already impressed by the performance of the classic Up model, but the Ghost version takes it to another level. Diving to 20 meters and feeling completely at ease means that even legs accustomed to carbon fins won’t feel the difference.

Design: 10 The biggest challenge—aside from ensuring durability—was maintaining transparency. The result? A revolutionary camouflage effect, with the fin blending seamlessly into the seabed. A true chameleon!

Value for Money: 7 The price is not the most affordable, but it’s fully justified by both performance and aesthetics—especially considering that it’s a one-of-a-kind product.