I once read that big container ships with certain stock, like oil, or coffee wait outside harbours until the price of f.i. coffee has risen 0,01% in the market so they can make more profit. Maybe this is what is happening
Not with container ships !!!! The cargo on the containers is usually way too much varied for things like this. Believe me, if there is something those ship operators do not want is extra time at sea or burning fuel without reason.
What you mention does happen A LOT though with OIL vessels. When I returned from the Arcadebarn (R.I.P.) meeting a couple of years ago, flying back from Essex with a turbo-prop plane, and thus not flying any higher than 7 km. I was BAFFLED by the amount of orange (=dangerous cargo) ships scattered all over the North Sea, which indeed are often just waiting there for prices to rise. This was also documented for TV a long time ago.
We are all at the mercy of those evil traders !
Oh guys, maybe the ship had to wait for a pilot to come aboard. Ships this size must have a local "pilot" on board who knows the local waters of that area/port really well and takes charge of the ship for entering the harbors.
Something like this (great time-lapse video of a Rotterdam pilotage) =>
http://www.youtube.com/watch?feature=player_embedded&v=C79ux3Qik5kAlso, sometimes simply have to wait to enter harbors, much like airplanes at airfields....