The submarine, of the brand Project 877 Paltus, was followed by a Russian corvette and a service ship.
The submarine has probably been on a Russian shipyard for repair and was now on its way to other waters via the Sound.
The video above shows how the Russian crew members stand on deck and check during the journey north through the Sound.
At times, the submarine was also joined by the Danish Navy.
But the Swedish navy stayed away.
- We keep track of all boats moving in the Baltic Sea.
No one crosses the Sound unnoticed either.
But this was a normal transport and it is not something we care about, says Rebecca Landberg, the navy's communications manager.
In the video above, you see the submarine pass by Helsingborg.