For this we need to start a new game with bots. I believe you are forced to start with two bots, so we need to kill them.
First, tell both bots to follow you to a ballast tank and then tell them to "wait". Weld the ballast tank closed and then, while still docked, tell the sub to move down. This will fill the ballast tanks. Once both bots have suffocated, buy fuel rods and welding tanks, then accept the mission and disembark.
I would recommend rushing the 500 or 600 meters to the objective, but since you are now alone be sure to deal with any hostiles if they start poking holes in your sub.
Once you arrive at the next station you should recieve the achievement. The only requirements are that you are the only one alive when the round starts and ends.