If you do not have a suitable vehicle, I recommend you to rely on an organized tour.
Swimming for more than 20 minutes is not recommended due to the high level of the salt.
The road is not paved, so if you do not have a suitable vehicle, it is better that you rely on a tour operator.
The Lagunas Escondidas de Baltinache are located 58 kilometers from the village of San Pedro de Atacama. Taking the road towards Calama, after about ten kilometers, on the left, an intersection with a small wooden sign indicates the way to follow to reach the lagoons.