Spot the glaring fact-checking failure in this article...
How about you just point it out to save everybody some time?
There are two reasons for it to be there: one is that a glut in cargo ship availability (due to the long order cycle) has coincided with the recession, so that the expected growth in shipping has stalled. Hence the large number. As for the location outside Singapore, it's handily just north of the equator and so not subject to tropical storms and weather patterns, meaning it's the handiest place is Asia to park a ship without paying port fees.
Sure, it's interesting that there's so much unused capacity gathered in one place, but 'secret'? I think not.