If you have a chance, the rivers to the south of Rotterdam are a surreally tranquil place - utterly flat and tideless, with good winds causing mere ripples and a population as friendly as the Dutch are supposed to be, when not permanently hassled by 'drug tourists' and stag do's (as they are in Amsterdam).
However the sea lanes around there are some of the busiest in the world, with monster container ships and tankers hooning along in a constant stream, 24 hours a day. Crossing them feels a bit like being a microscopic tortoise crossing the M25...
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