On this 18-hundred-ton Ahn Jung-geun submarine an order to dive is called out.
Within a matter of seconds, the submarine disappears underwater.
After exploring the waters, the submarine detects an enemy vessel and locks it down as a target.
It then secretly approaches the vessel and launches a torpedo sinking the ship.
The mission is a success.
"Submariners are designed to deter North Korea's provocation in the deep sea and are currently playing a big role in securing our national interests."
Submarines are key strategic weapons, but from the inside they look cramped and all but easy to work in.
With tiny bunks and a cafeteria, 40 crew members have to live in these tight quarters for months at a time.
But it's not just about the size of the submarines.
One of the greatest challenges is that South Korea only has 10 submarines, while North Korea has seven times more.
Experts say that Seoul needs to increase its numbers in order to engage in a fair fight.
Since the 80s there were seven confirmed cases of submarine provocations from the North and many more that went unconfirmed.
According to the South's Navy, it is scheduled to produce more submarines to better prepare for North Korea's threats underwater.
Kim Hyun-bin, Arirang News.
Reporter : firstname.lastname@example.org