Why Are Most Military Submarines Painted Black?

Military submarines (as opposed to submersibles) are among the most intimidating vessels one can encounter. They can search, track, and engage both land and sea vessels while staying hidden for extended periods — some of the most advanced nuclear submarines can dive deep into the ocean for months without succumbing to the immense pressures deep seas are known for. And many subs are equipped with nuclear missiles that have the potential to level entire theaters of war. 

These vessels have always played an important role in warfare. During World War II alone, U.S. submarines played a crucial role in destroying Japanese supply lines and ships. They also came to the aid of numerous downed pilots, demonstrating that these powerful vessels could do more than just destroy. By the end of the war, American submarines had sunk more than 1,300 enemy warships in the Pacific alone. 

When asked what makes a military submarine so intimidating, you might quickly mention its agility or its extensive arsenal. But one of the main reasons subs project such an intimidating aura is their ability to remain unseen in most situations. Although they're equipped with systems to enhance their stealth capabilities, a key factor is the black color many navies around the world paint them in. Let's explore why many gravitate toward this color and how it improves submarine stealth.

Muhammad Ali once said, "Your hands can't hit what your eyes can't see," as the Hollywood Reporter noted. While this statement referred to the boxing ring, it applies to warfare, too. You may have noticed military ships and aircraft painted grey or troops wearing gear that mimics their surroundings. As far back as the early 20th century, military forces like the French were incorporating ways to obscure their troops from the enemy's eyes. 

Military camouflage is typically determined by the environment where it will be used. In oceans and seas, which define the submarine's area of operation, the environment varies in color. The most recognizable color for many people there is blue, because water molecules absorb the red wavelengths from the light spectrum, reflecting the blue wavelengths back to our eyes. However, as you descend deeper, the colors fade significantly, and eventually, everything is pitch black. In such environments, a black submarine blends in seamlessly. However, achieving this stealth is more complex than you might think.

Black is the perfect color for obscuring a submarine, as it reflects the least light. This is especially important if the submarine is near, or has breached, the water's surface, where warships and fighter jets might easily pick it up. Black becomes even harder to spot once night falls, letting the sub operate near the surface without risking its position. 

Once the vessel dives below the sunlit zone, the color still holds an immense advantage, mainly because of the material used in the paint. At depths greater than 656 feet, visibility from sunlight is near nonexistent. You might assume a submarine's color wouldn't matter here, but this is actually where it excels. 

Sonar rules the deep ocean, enabling the identification of objects through sound waves. Submarines use echo-fighting coatings and tiles on their hulls to absorb and scatter sound waves, making subs invisible to enemy vessels. These coatings and tiles also absorb noise from the vessel's own machinery, personnel, propeller, and interactions with water, further concealing it from the enemy. 

And they contain carbon black – the source of the black color you see when looking at the submarine. Carbon black doesn't just excel at stealth; it also enhances the hull's durability, fighting wear and tear, and helping the submarine's hull endure the pressures of diving and surfacing.