In Figure 1, the small round circle includes the headwaters of two
tributaries of the Grijalva river and the headwaters of two tributaries of the
Usamacinta river indicating that the headwaters of the two longest rivers in
Mesoamerica are within 20 miles of each other and are located in a
rugged mountainous area. Since the search party was undoubtably
following directions handed down by word of mouth, it is likely that these
directions instructed them to find the headwaters of the Sidon river and
follow the river till they arrived at Zarahemla. It is very probable that they
encountered one of the headwaters of the Usamacinta river and unaware
that there was another large river in the area followed it down into the
lowlands and eventualy to the delta of the Usamacinta which as per their
description  of the journey is indeed a land of many waters. Mosiah 8:8
Traveling westward from this area they arrived at the mouth of the Grijalva
river where they encountered the territory from which the Zarahemlites had
left to come up into the land of Zarahemla. It is likely that Ether may have
entrusted his record to someone and that it eventually ended up in this
area to be found by the search party. Remember that it was in this area
that the Mulekites landed and came in contact with Coriantumr. Omni 1:21

It is obvious from the history in the Book of Mormon that the search party
lost their way but it is not logical that they should start out without some
instruction and description of the route they should follow to return to the
Land of Zarahemla. If they had simply gotten themselves lost, they would
have recognized it much sooner and returned for better information.
However, if they were following the wrong river they would not realize their
error until they had traveled a distance at least as far as they thought it was
to Zarahemla. By that time it was too late to turn around and when they
found the remains of a great battle they assumed that the Nephites had
been destroyed and so returned to the Land of Nephi by the same route
that they had previously followed. The fact that they were able to return
shows that they kept track of their travel route and were able to follow it
back to its origen.

When Mormon inserted his description of the geography relative to the
King's Proclamation, he was careful to describe the head of the River
Sidon as running east to west as opposed to the head of the Usamacinta
which runs from west to east. It is tempting to think he did this because he
realized the mistake made by King Limhi's search party. Or it might just be
that he was more careful in his description than were those who instructed
the search party.
Figure 1

Tale of Two Rivers