The Narrow Neck of Land

The narrow neck of land, mentioned repeatedly in the Nephite record (Alma 22:32; Alma 50:34; 52:9; Hel. 4:7; Morm.3:5; Ether 10:20), is the key to Book of Mormon geography. Most researchers consider it to be an isthmus which connects the land southward and the land northward. If this geographic feature could be identified it would solve the riddle of Book of Mormon lands, and then all else would naturally fall into place. Many different possibilities have been suggested, from the Isthmus of Panama to a penisula between two of the Great Lakes. However, in my opinion all of the suggested sites fail to meet the criteria set forth in the Book of Mormon.

Most recent researchers feel that the Isthmus of Tehuantepec, in southern Mexico, is the narrow neck of land. However this site also seems to fall short of the mark. Naturally I have my own opinion which I will present shortly. But before we talk about specifics, let us consider the criteria for this landmark which are outlined in the Book of Mormon.

Now that we have the criteria in place, let us proceed with my proposal.


I suggest that the Isthmus of Rivas on the Pacific side of Nicaragua is the narrow neck of land referred to in the Book of Mormon. This may seem odd to most students of Book of Mormon geography as this minor isthmus does not appear to be a significant feature which would isolate Nicaragua from Costa Rica. But in fact it is.  So be patient and I will try and illustrate the logic of this proposal.

The Isthmus of Rivas is a low-lying strip of land between the Pacific Ocean on the west, and Lake Nicaragua on the east, with a northwest-southeast orientation. On the western side the isthmus is composed of a low range of coastal mountains parallelling the Pacific coast. This range reaches a maximum height of 1700 feet. A lowlying plain, about 4 miles wide, and averaging 100 feet above sea level, forms a corridor bordering Lake Nicaragua. The coastal mountains wedge eastward at the southern end of the isthmus to form a narrow corridor along Lake Nicaragua leading southward into Costa Rica.  At the narrowest point on the isthmus, near the city of Rivas, the isthmus is 12-15 miles wide. Its north-south length is approximately 100 miles. At the southern end of the isthmus it is approximately 25 miles wide, from the lake to the Pacific Ocean.  This area of Nicaragua has a wet season from May to December and a dry season from January through April. It averages 35 inches annual precipitation and the average temperature ranges from 20 degrees Celsius (68 degrees Fahrenheit) to 44 degrees Celsius (93 degrees Fahrenheit).

Due to its topography, climate and open landscape, the Isthmus of Rivas has been the natural and preferred route of travel since ancient times. It presents few barriers, and provides many amenities to the traveler. All land traffic, whether north or south is naturally funneled through this area. It was of course natural that the Panamerican Highway would be built along its gentle course.

In close association with the Isthmus of Rivas is the adjacent Lake Nicaragua. This lake is the largest freshwater lake in Central America, and the dominant physical feature of Nicaragua. The Indian name for the lake was Cocibolca, meaning sweet sea”; the Spanish called it Mar Dulce. It is oval in shape, has a surface area of 3,149 square miles, is 110 miles in length, and has an average width of 36 miles.  It is about 60 feet deep in the center, but reaches a maximum depth of 200 feet (105 feet deeper than sea level) southeast of the island of Ometepe. Its surface is 95 feet above sea level. More than 40 rivers drain into the lake, mostly from the eastern side.

It has been suggested (1) that Lake Nicaragua, together with Lake Managua to the northwest, originally formed part of an ocean embayment or gulf that, as a result of volcanic activity and tectonic uplift, became an inland basin containing the two lakes. The ocean fish thus trapped adapted themselves as the water gradually turned from saltwater to freshwater. It should be noted that Lake Nicaragua is possibly the only freshwater lake containing oceanic animal life, including sharks (2), tarpon, swordfish and sawfish.

The San Juan River, which drains the lake and connects it with the Caribbean Sea to the east, is 112-miles long and averages 1000 feet in width. This river is an effective barrier which separates the land masses of Costa Rica and Nicaragua. On its eastward course to the sea, it passes through a densely forested region which is the least inhabited area of either country. This lack of habitation is due to the inhospitable nature of the country and climate (dense jungle, high rainfall, high humidity and high temperatures), and to the difficulty in building and maintaining roads and trails. Even in our day no bridges span the river, no ferries cross it, and no interconnecting roads end at its banks. At the outlet from Lake Nicaragua, and more so in the Caribbean delta region, there are vast areas of swamp and wetlands blocking any attempt at foot travel. Historically, the river has been a route for shallow-draft boat traffic, and was once even considered the favored route for the interoceanic canal until that route was replaced by the Panamanian one (not for a lack of feasibility, but rather for political reasons.)  

Over the last 2000 years the numerous volcanoes which flank the southwestern side of the San Juan River basin have contributed vast amounts of silt to the drainage through their periodic eruptions.  For example, one study (6) of the relatively young Arenal volcano measured 20 meters (65 feet) of ashfall sediments at a point ten kilometers from the volcano.  In view of this extesive alluviation over the last several millenia, it is entirely possible that in Book of Mormon times the San Juan River Basin was lower in elevation, increasing the size of the river, and possibly even featuring a Caribbean embayment.  However, this proposal is valid even with the present topography.  Increasing the  size of the river, and submerging the present wetlands under the Caribbean, would only enhance  the San Juan's potential as a barrier.

How does the Isthmus of Rivas match the criteria outlined above for the Narrow Neck of land? It is oriented in a northwest-southeast direction, bordered on the west by the Pacific (west sea), and on the east by Lake Nicaragua (east sea). Lake Nicaragua divides Pacific Nicaragua from the Caribbean side, hence "the place where the sea divides the land" (Ether 10:20.)  It is recognized as the ancient Pre-Columbian trade route between Mesoamerica and South America.  The natural travel route begins near the Pacific coast at La Cruz, Costa Rica and goes northeast following the northern bank of the Sapoa River to where it flows into Lake Nicaragua.  Then it turns northeast following the shoreline of the lake.  The lower Sapoa Valley, near Lake Nicaragua, narrows due to encroaching mountains on either side. These same mountains constrict the southern shoreline of the lake where it meets the Sapoa Valley.  I believe this narrow corridor is the "narrow pass" referred to several times in the Book of Mormon. The balance of this immediate area is covered with rough mountainous terrain which is not conducive to easy travel.  The isthmus itself is narrow enough to cross on foot in a day  (See discussion on distances.)

The Rivas Isthmus is much lower than the Guanacaste highlands, to the immediate south in Costa Rica, which reach heights above 6000 feet. The land mass of Costa Rica/Panama could easily be considered an "isle" and is at least 80-90% surrounded by the Pacific and Caribbean. This is something that the average Nephite would have been visually aware of. By climbing one of the taller mountains in Costa Rica, one can see the oceans on both sides, and possibly Lake Nicaragua and the isthmus as well. In conjunction with the lake and the San Juan River, the isthmus forms a natural boundary between the lands to the north and south.

There were substantial native populations at the time of the conquest. Oviedo (3) estimated that there were 600,000 people living in Nicaragua when the Spaniards arrived. Martyr records that there were 6 large towns with 2000 houses each. Squires (4) observes that Leon, Nicaragua, at the north end of the isthmus, was built on, and adjacent to the original Indian town of Subtiaba, and Granada was established next to the native town of Jalteba. Although no ruins similar to those in Mexico or Guatemala have been found in Nicaragua, there are many large stone carvings similar to the Mesoamerican ones. These have mainly been found on the islands in Lake Nicaragua where they had been taken and buried by the natives to avoid destruction by the Spaniards. There are many ancient sites with evidence of habitation. Some of these have been excavated and studied. However, south of the Isthmus of Rivas, there are none of the large stone Maya, Aztec or Olmec ruins of Jaredite design.

The isthmus is a strategically significant area, and could easily be fortified by a large military force, concentrating the majority of its forces at the "narrow pass" (the level plain next to the lake, and the narrow section at the mouth of the Sapoa River).  To avoid these areas, an invading army would have to traverse the  rough mountainous terrain which borders the river and the lake.   

I believe that the ancient archeological site of San Dimas (7), near the mouth of the Sapoa River, corresponds to the city of Desolation, and that the Sapoa would have formed the border between the lands of Bountiful and Desolation, much as it parallels the modern border today.  The city of Teancum could possibly be identical with the ancient archeological site of San Jorge (8), near Rivas, Nicaragua, on the shore of Lake Nicaragua.  This site is about 20 miles northwest from the site of San Dimas.  The beautiful horsehoe Bay of Salinas, on the northwestern Costa Rican coast, and the associate archeological site of Las Marias, may have been the location of Hagoth's shipbuilding activities.  

 It is difficult to assess the lack of trees during the Nephite era; however, the isthmus is quite open with savannahs and somewhat sparser tree cover than is common for the area. But something such as this can vary greatly over a thousand years. The Jaredite plague of poisonous snakes is also difficult to assess. This area would certainly be amenable to such an occurance. Once the isthmus were blocked in this or any other way, human and animal traffic would be impeded. This would not be so in the case of a land bound barrier. Neither mountains, wilderness, swamps, or jungle, no matter how rugged or impenetrable, can prevent wild animals from passing through. And a persistent man can penetrate the worst jungles, and pass through the most rugged mountains, if given the time and the motivation. But wide bodies of water prove to be effective barriers for man or animal, and will impede man unless he uses watercraft. Lake Nicaragua, the Pacific Ocean and the San Juan River basin combine to create such a barrier. It should also be noted that there is currently a healthy population of snakes in the Guanacaste area of Costa Rica, south of the Rivas isthmus.

The Rivas region appears to have been a natural dividing line between northern and southern cultures.  Solc (5) observes that "The territory of Nicaragua and Costa Rica is undeniably the meeting-place of the Central and South American cultures [Jaredite and Nephite?]. The Maya and Mexican influence is evident as far [south] as the Nicoya peninsula [in northwestern Costa Rica.]”

Considering all these factors, it appears that there is a strong correlation between the Isthmus of Rivas in Nicaragua and the narrow neck of land described in the Book of Mormon.



(1)  There are those who contest this view. They feel that the area never was a part of the sea, but that the lakes have been formed as a result of subsidence along the Nicaraguan rift. In this view the area is not being elevated but is subsiding. However I feel that at least the idea of subsidence is incorrect. Refering to plate tectonics, western Nicaragua is part of the Chortis Plate which is being subducted by the Cocos Plate. This would normally result in elevation rather than subsidence. Subsidence would only be possible with an extenstional environment, not a compressive one. However geological studies of western Nicaragua have shown that "Compression due to subduction [during the middle Eocene] resulted in the formation of a fold belt, parallel to the trench [the westward fore-arc trench], in the Rivas Isthmus." And again "In the Miocene, compression and uplift of the Rivas Isthmus, accompanied by an intrusive activity, formed anticlinal features cored by shale diapirs. In the Upper Miocene and up to the Present, a platform siliciclastic depositional system prevailed, with the influence of local deltas. The eastern parts of the basin were uplifted along a coastal flexure, and the whole Tertiary section is outcropping along the Pacific coast." "From Late Miocene to the present, positive uplift of the Nicoya and Santa Elena Peninsulas occurred." FRAMEWORK

Therefore it is obvious that the Pacific coastal region is being subducted with associated compressional forces and uplift of the subducted plate. Of course, it is also obvious that the Nicaraguan rift is depressed compared to the relatively uplifted areas to the east and west. But this does not mean that the entire Chortis Plate is not currently being uplifted, but that the rift area is at a lower elevation than its adjoining uplands, and that at some time in its history it was depressed in relation to them.

Evidence that this area is still undergoing subduction is the fact that it is one of the most active tectonic areas in the world, with numerous active and recently active volcanoes, and frequent siesmic activity. This is also corroborated by evidence from Costa Rica indicating that this area is being uplifted at an average rate of 1-3 mm./yr.

(Additional references on the geology of the area:,,

(2)  A recent study has questioned the uniqueness of the Nicaraguan shark. Electronically tagged sharks have been traced swimming up and down the San Juan River. This has led to the notion that sharks can adapt to both fresh and salt water. However if this were the case, would you not find shark in all the fresh water rivers and lakes connecting to the sea?

(3)  Oviedo y Valdes, Gonzalo Fernandez de. Historia General de las Indias, Islas y Tierra Firme del Mar Oceano (1945; first 19 books originally published in 1535).

(4)  Squires, E.G. Nicaragua; its People, Scenery, Monuments, Resources, Condition, and Proposed Canal. Harper and Brothers, Publishers. New York. 1860.

(5)  Solc, Vaclav.  Chirique Culture.  Naprstek Museum.  Prague.  1970.  p.12.

(6)  Melson, William G.  Prehistoric Eruptions of the Arenal Volcano, Costa Rica.  Vinculos 10:34-59, 1984.

(7)  Lange, Frederick W., and Murray, Thomas A.  The Archaeology of the San Dimas Valley, Costa Rica.  Univ. of Northern Colo.  1972.

(8)  Healy, Paul F.  The Archaeology of the Rivas Region, Nicaragua.  Wilfrid Laurier Universtiy Press.  1980.  p. 41.