Nato was doing drills in the area, the “front fell off” the Estonia which was suspected to be from collision with a submarine (I think that’s what the conspiracists decided) or an explosive charge (I think there was unusual wear on the joints that hinted at explosives), the mayday calls were delayed and non standard, and the entire wreck was entombed in steel & concrete to prevent any further investigation. There’s more but I don’t remember and the truth is out there

Occam’s razor: when in doubt, blame NATO