Swedish officials are investigating reports of a foreign submarine in its territorial waters.
This comes after someone snapped a grainy photo on Friday of a vessel, which appears to have been a submarine.
The Swedish military has received several reports from witnesses saying they saw what appears to have been a vessel submerge in waters around 30-miles off Stockholm.
Anders Grenstad is a rear admiral at Royal Swedish Navy.
"It could be a submarine, or a smaller submarine. It could be a diver using some form of moped-like underwater vehicle and it could be divers that don't have any business in our territory. That's where I think you have the span of what could be foreign underwater activity."
The Swedish military says the sightings have taken place in "an area that is of interest to a foreign power."
The incident has reawaken memories of the Cold War when Sweden repeatedly tracked Soviet submarines along its coast.
