Porto Ercole is generally safe for solo female travelers. As with most destinations in Italy, the risk of violent crime is low, and the locals are typically friendly and welcoming. However, it's important to take usual safety measures like staying aware of your surroundings, especially at night, and avoiding displaying expensive jewelry or other valuables. You may also experience minor issues like pickpocketing in crowded areas. Overall, the town and its attractions are safe to explore solo with a bit of caution.