Estonia Explosion Not Ruled Out

In the 1994 accident 852 people died, the majority of them Swedes, when the ferry went down on its way across the Baltic Sea from Tallinn to Stockholm.

An inquiry in 1997 concluded that the tragedy was caused by a fault in the bow visor door letting water into the car deck, but some survivors say they heard an explosion onboard.

The Swedish government asked researchers to look into why the ferry sank so quickly and they say it is possible a blast could have blown a hole out of the ship.