The river Sidon was the only named river in the New World and the place where the most travel between lands occurred. Yet, no one ever went downstream on the river Sidon from the land of Zarahemla. A few lands could be identified as being northward of the land of Zarahemla, but no one ever traveled downstream on the river Sidon and there are no confirmed locations of lands or cities downstream from the land of Zarahemla. The land of Zarahemla was not on the coast, so there is a big vacancy in the map about the river Sidon between the land of Zarahemla and the coast. The internal map does not even include the mouth of the river Sidon. The information is not in the Book of Mormon, so the downstream portion of the river Sidon is not on the map.

Mouths of rivers are common locations for ports and cities. That no cities were mentioned at the mouth of the river of Sidon is interesting. I'm not the first person to recognize this, but many maps of the Book of Mormon geography tend to ignore this fact.