Here is an interesting question, why are submarines black and not any other colour? And no, it's not for better camouflage.
Back in the 1940s, The US military underwent a secret mission in order to test out various colours of submarines to validate their camouflage capabilities. Some were painted light blue, dark blue, black and even green. As their findings showed thereafter, the darker blue submarine performed the best in deep tropical waters, and that the black was one of the worst-performing.
What the findings also showed was that the paint itself started rapidly deteriorating due to the pressures involved in submarines.
As it turns out, modern submarines are not even painted at all. Submarines appear black due to their outer construction being composited by a mosaic of rubber tiles. The rubber on the outer surface layer of submarines proves to be highly durable and can withstand colossal pressures. Plus, it's a brilliant sound dampener to help the sub to go undetected by sonar systems.
However, rubber is naturally white in colour. Even in early tyres, they were white. But why are tyres and submarines black? Tyres are black nowadays due to the infusion of carbon black composites within the rubber, which increase the lifespan of tyres up to 2000%. The same goes for the carbon black infused rubber tiles on modern submarines.
Take a look at the video below by YouTube channel, Not What You Think, on Why Are Submarines Black And Cruise Ships White?