Originally Posted by SlowButSteady
There are hundreds of millions of containers shipped every year. Ten thousand is a pretty small number in comparison.
Even if one limits the area to that of the theoretical "shipping lanes", one would have to search a huge area of the ocean floor to find many containers. You might also note that shipping containers are not particularly robust. Their "skin" is fairly thin sheet metal, and not particularly corrosion resistant at that. A ship, made of nice thick plate steel, may last many decades on the ocean floor, but I doubt a shipping container, made mainly of corrugated sheet metal, would have nearly such longevity.
Anyone who has been up close & personal with shipping containers (I have) will tell you they are not lightly built - depending on the size and type, they can weight 5000 - 8000 lbs empty and over 65,000 lbs loaded. They seal pretty well (only some have vents) since they are designed to keep cargo dry. Though the corrugated walls may only be 1/8" plate (not exactly sheet metal...), the corners are built much heavier to permit stacking them 4 -6 high. Did I mention they have sharp corners? In the event that one of these containers is afloat, even waterlogged but not sunk, it can drift for many miles on the currents, so even far from shipping lanes they are a danger. As to longevity, they won't rust out for years - they are designed for salt water environment. IMO, next to tropical storms, shipping containers are probably one of the most dangerous things a blue water sailor can encounter.