It isn't. About as many ships and planes and things disappear there as you'd expect, given the size and density of shipping. Kusche wrote a book in 1975 that basically pointed out that the mystery of the Bermuda Triangle can't be solved because there's nothing to solve.
 Sink. They sink. Everyone says 'disappear' as if they poof into nothingness in plain view of onlookers. When a ship enters any other stretch of ocean and is never seen again, it's a foregone conclusion that it sunk, but in the Bermuda Triangle it, instead, mysteriously disappears.