Although it’s always important to be cautious and travel with attention, worrying about your safety on Isla del Sol should not be an issue. The island it fairly secluded, as you have to boat on and off, and aside from wanting to sell you handicrafts, the locals more or less keep to themselves. It’s likely that your biggest worry will be other travelers. Bring a lock to keep secure your personal belongings, and maybe to use on the hostel door. While the accommodations usually offer one, you may feel better providing your own.