During our rafting trip on the Usumacinta we spent 2 nights at a Maya ruin known as Piedras Negras.
These ruins are only accessible by boat and our guide estimates that at most 200 people a year visit them. We spent an entire day camping at the site and were given an extensive tour by our guide. The site has had minimal work done to it for preservation. For the most part the jungle has reclaimed a town that is estimated to have had a population of around 2500 at its peak.
While this site is remote it has been essential for the deciphering of the Maya language. There are numerous stones with various inscriptions throughout the site. In some cases the local caretakers have built structures to cover softer stones to slow their erosion.