 Disguising himself as a cook and interpreter, he studied the traders , merchants and others who visited the castle, as well as the arrival and departure of ships.
<coherence>  Disguising himself as a cook and interpreter, he studied the traders , merchants and others who visited the castle, as well as the arrival and departure of ships.
 Disguising himself as a cook and interpreter, he studied the traders , merchants and others who visited the castle, and the arrival and departure of ships.