A friend told me to seek you out, after I shared my traumatic horror movie memory with him, and so, here I am. I'm afraid, though, that my trauma might be too esoteric to be pinned down, but I hope I'm wrong.
It was a movie I saw in Puerto Rico as a kid, it was in Spanish, so it's quite likely that it was a Mexican/Latin American production. The setting is a boat in the Bermuda Triangle--I remember the ad campaign cashing in on the "mystery" surrounding the region. On that boat is a family, including young boy and girl siblings, and her doll. Naturally, the boat eventually becomes adrift at sea, and the family comes across some survivors from another ship. These are merchant marine types, who quickly hatch a scheme to take over the family's boat for their aims.
But the thing about the area they are in is that some malevolent spirit(s) reside there, and it(they) take over the will of those who are morally and mentally weak, and, somehow, the doll. Here's where the trauma comes in, there are numerous sequences where the doll threatens the kids, and is even responsible for the deaths of one of the kids and a couple of the adults...
That's if I remember correctly. It's been almost thirty years since I saw the flick, and I'm sure it left an impression despite being a cheap z-grade movie because of that damn doll. I can't be more specific than I've been however...
UNK SEZ: I think I do know this one! I believe our pal Francisco once wrote in about it (HERE)! Could it be 1978's THE BERMUDA TRIANGLE directed by RENE' CARDONA JR.? There's definitely a creepy doll in that one!