WION Decodes | Hidden secrets of submarines that most people never know

When nuclear submarines go deep underwater, they stay submerged for many weeks or even months. All doors and systems remain tightly sealed from the outside world. The sailors keep breathing inside this closed space, so carbon dioxide (CO2) slowly builds up in the air. For a common person, think of it like sitting in a small locked room for days – the air becomes heavy and unhealthy. Too much CO2 can make people feel sick or even become dangerous.

To solve this problem, submarines use special machines called CO2 scrubbers. These machines use a chemical known as amine. When the amine is cool, it acts like a sponge and absorbs the harmful CO2 from the air. When the same amine is heated, it releases the trapped CO2. This cycle of cooling and heating keeps going on and on inside the scrubber. The removed CO2 is then safely pushed out into the ocean. In this way, the air inside stays fresh and breathable for the crew.

This system works very well and saves lives. But it has one big drawback. The amine chemical creates a very strong and unusual smell that spreads everywhere in the submarine. Over time, this smell gets into the walls, clothes, and even the skin of the sailors.

Life inside a submarine is full of many other strong smells too. There is the aroma of food being cooked daily, fumes from hydraulic oil used in machines, small traces of diesel exhaust that sometimes leak in, bad smells from waste tanks, and the natural body odour that builds up when many men live together in a tiny closed space for long periods. All these smells mix together and create a unique, powerful odour inside the submarine.

At first, new crew members find this smell strange and heavy. But slowly, their noses get used to it and they stop noticing it. They live and work as if everything is normal. However, anyone coming from fresh outside air can smell it immediately and clearly.

There is a real story that shows this. Once, a submarine sailor was flying home for vacation in normal civilian clothes. He sat next to an elderly woman on the plane. They were talking casually when she suddenly asked, “Are you from the submarine service?” The surprised sailor replied, “Yes, how did you know?” The woman smiled warmly and said, “My husband served on submarines. I can never forget that special smell.”

This small incident shows how even after many years, the hidden smell of submarine life stays in the memory of families. For the sailors, it is part of their tough but proud journey – living in a steel world under the sea, breathing cleaned air, and carrying that unique smell as a silent reminder of their service.