Zakynthos enjoys a very low crime rate, but precautions should still be taken, especially in heavy tourist areas. Regrettably, a lot of petty crime is down to the tourists.
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National language is of course Greek, but pretty much all inhabitants also speak English probably due to the fact that British tourists are by far the largest fraction of tourists. German is spoken by many as well, and Italian is well-represented, especially in the northern parts of the island.