We visited the Sillustani Archeological site. It is right by the Umayo lagoon, which is about 26m deep.
The site is a pre-incan burial ground where you can see the tower-like structures, called chullpas, which are tombs that are built in and above ground. The tallest one is 12m high. Most of the tombs are from the Colla people, who were conquered by the Incas. Also, some of the tombs were from the Incas. You can tell the difference in the structures because the Incas would always polish and shape the stones, whereas the Collas just piled them.
All these towers/tombs were for the elite and their wives. Many were destroyed by robbers searching for gold.
I do not have much more information because it turns out our guide was not too great and that morning while we were at the site I was firing him…but it was still very interesting and the lagoon is beautiful!