<prompt> Translate the following text to EnglishHali ya uchafuzi wa maji hutofautiana kutoka mwaka mmoja hadi mwingine, lakini fuata sheria ya kawaida ya kuepuka kuzama katika ujirani wa karibu wa bandari kubwa za viwanda za Genoa, Naples, na Palermo.  <response>: Conditions of water pollution vary from year to year, but observe the general rule of thumb of avoiding a dip in the immediate vicinity of major industrialized port Genoa, Naples, and Palermo. 