In Alma 50:34 we find the phrase, “the narrow pass which led by the sea--on the west and on the east.” This phrase allows several interpretations:
(1) First, it may mean that the “narrow pass” runs in the middle of the “small neck,” which neck, according to Alma 22:29-34, was “between the land northward [Desolation] and the land southward [Bountiful],” and the distance “on the line Bountiful and the land Desolation, from the east to the west sea” was “a day and a half’s journey for a Nephite.” .
(2) Second, the “narrow pass” might have been on one side (the right side) of the “small neck of land” which was between the land northward [Desolation] and the land southward [Bountiful].“ Assuming a Mesoamerican setting, and according to the theory of John Sorenson, movement through the Isthmus of Tehuantepec on the Gulf of Mexico side of the divide is extremely difficult unless a narrow ridge of land is followed. According to David Palmer, movement through the Isthmus of Tehuantepec on the Gulf of Mexico side of the divide is extremely difficult unless the ridge running from Acayucan past Minatitlan is followed. Elsewhere the area is too swampy for travel. In fact, going back through time, it appears that there never have been trade routes crossing the isthmus in a true east-west direction except along that ridge and along the Pacific side. According to Zeitlin (1979:168), both the Pan American and Transisthmian highways … ”closely parallel ancient paths of trade and communication.“ There are some Nephite-period ruins overlooking the road between Acayucan and Minatitlan. One such mound can be seen along the highway twenty-five kilometers from Acayucan. There are many such ruins which have never been documented due to inadequate archaeological surveys in this area of the lower Coatzacoalcos River basin… . It seems likely that the gravelly ridge crossing this swampy area [making a ”sea--on the west and on the east“] and ending at the major ford on the Coatzacoalcos river could be associated with the narrow pass at which Teancum was able to stop the flight of the people of Morianton… . The ”borders" of the different lands appear to have been rivers in many cases, which suggests that the encounter took place near the Coatzacoalcos River. [David A. Palmer, In Search of Cumorah, pp. 31-32] [See the commentary on Alma; 52:9; Helaman 4:7; Alma 63:5; Mormon 3:5-7]
Note* If the place where Teancum intercepted Morianton became famous and as it became populated, they named the city “Teancum”; then, the city Teancum (mentioned in final Nephite retreat--Mormon 4:3 in accordance with Mormon 3:5-7 which relates the battles just before the Nephite retreat to the city of Teancum) fits very nicely into a location “near Desolation” and near a “narrow pass,” and could possibly “lay in the borders by the seashore” (east), “near the city Desolation.”
(3) The third point of view is a variation of the second point of view, meaning that (a) the “narrow pass” had to do with major travel and trade routes; (b) one “pass” led along the “sea-- … on the east” (Gulf Coast), but another “pass” also led by the “sea--on the west” (Pacific Coast).
In Mormon 3:5-7, there is reference to the final Nephite battles, and the location of Mormon and his armies: “I did cause my people that they should gather themselves together at the land Desolation to a city [”Desolation“--Mormon 3:7] which was in the borders, by the narrow pass which led into the land southward… And it came to pass that … the Lamanites did come down to the city of Desolation to battle against us. According to David Palmer, there are no elevated areas within a hundred kilometers of the gravelly ridge near the mouth of the Coatzalcoalcos on the eastern side. Palmer goes on to cite Alma 63:5, which talks about Hagoth, who built a ship ”on the borders of the land Bountiful, by the land Desolation, and launched it forth into the west seaby the narrow neck which led into the land northward.“ Thus, according to Palmer (Cumorah, p. 33) ”it seems to me quite likely that this was a different pass" (on the west coast).
(4) A fourth point of view might incorporate all of the above. The “narrow pass” could be the same as the “narrow passage” and the “small neck” A “narrow [trade] passage” could have run northward along the “sea--on the west,” then moved “west--->east” as the “small neck of land” between the land Desolation and the land Bountiful, then turned northward as a “narrow pass” along the “sea-- … on the east.”
[Alan C. Miner, Personal Notes]