Sifnos is one of the safest islands for solo female travelers. It is a quiet and peaceful island with extremely helpful and friendly locals. Crime rate is very low and there are hardly any reports of incidents involving tourists. There are well-lit paths even in rural areas during the night, which makes it very comfortable and safe to be out after dark. However, as with all travel, I always recommend using normal safety precautions such as not leaving your belongings unattended.