Dangers & Annoyances
Northern Chile is a very safe place all in all. In the rough-and-tumble mining towns like Calama, however, men may direct unwelcome leers and whistles at women, and should be careful walking alone at night. Many of the low-budget hotels in the region are now full-time residences of visiting miners, which may make for an unpleasant situation for single female travelers.
The currents on the beaches can be quite strong, meaning good surf, but less-than-ideal swimming. Signs saying 'no apta para bañarse' (not suitable for swimming) are posted on most beaches that have strong currents.
You should drive with your lights on during the day (and at night), and use caution when you see zona de derrumbes (rock-fall zone) signs.
Another thing to keep in mind is that there are still a few land mines in the desert around San Pedro, even in the touristy Valle de la Luna, and especially in the areas close to Peru. These were put down by the Pinochet dictatorship during tensions with Peru in the 1970s. While you're unlikely to step on one, you may want to think twice before heading out to remote border areas by yourself.