The first maps and descriptions of the Hispaniola were drawn by chroniclers such as Fray Bartolome de las Casas, Pedro Martir de Angleria and Gonzalo Fernandez de Oviedo who were travelling with the Spanish "conquistadores" in the sixteenth century: their maps used to describe bays, points, ports, valleys, cities, uses and aspect of the autochthonous inhabitants. The first map in which appears the topographical name "Sosua" as a map marker of the homonymous river is the map of Schomburgh of 1853.

old map sosua
Schomburgh map of 1853 with Sosua river

In "Geofrafia de la isla de Santo Domingo" of 1866 by Javier de Guridi we can find Sosua mentioned as a port from which "once" a lot of Caoba wood used to be exported.
Export of Caoba wood started before the indipendence of the Dominican Republic under haitian rule when General Louis Ferrand between 1805 and 1810 promoted wood exports to earn foreign currency, after the 1844 Indipendence the Caoba farms expanded in the North Coast and the caobas produced in the Puerto Plata Region used to be exported from the ports of Sosua and Cabarete.
On a 1906 map Sosua is marked as "villorios / aldeas" which in Spanish means small village, not just a rural settlement, actually the third village by size in the whole district of Puerto Plata.

old map Sosua
Map of  Puerto Plata discrict in 1906 

In the original  notes and geographic studies of Themistocles A. Ravelo (written circa in 1915 and later collected in the "Dominican Geographic-Historical Dictionary") Sosua is described as follows:

"SOSUA Port that is ten miles to the E. S. E. of Puerto Plata between the tip of the same name and Punta Payne; This port, also called Puerto Grande, has become very important for some time due to the large plantations of bananas established nearby and that have given life to the population of Sosúa, which was built on Punta Payne, on the eastern margin of the same port."

This small description, give us a clear clue of the fundamental role that the bananas plantation had for the growth and development of Sosua. 

Bananas were introcuced to the island of Hispaniola in the year 1516 by Fray Tomás de Berlanga, from the Canary Islands, despite their popularity in the tropics, bananas remained virtually unknown in the U.S. until the late 1800s. Bananas were formally introduced to the American public at the 1876 Centennial Exposition in Philadelphia which included a display of tropical plants. But bananas remained an expensive exotic fruit for years after their appearance at the Exposition.

The commercial success of bananas as a mass consumption fruit was the result of the import trade started by captain Lorenzo Baker, who started to import bananas from Jamaica to resell them with huge margin and profits in the US, his first load to New Jersey was in 1870. In 1885 he and Boston businessman Andrew Preston formed Boston Fruit Company. In the year 1896 Boston Fruit Company started a banana plantation in Sabana de la Mar in the Dominican Republic and shortly after that it started the bananas plantation of Sosua.  In the year 1899 Boston Fruit Company became United Fruit Company after the merger with Minor Cooper Keith’s bananas operations which created the largest banana monopoly in the world.. 

Why United Fruit Company at the end of the XIX century started a bananas plantation in Sosua?
1-Sosua had a working port which was used before 1866 to export wood
2-Sosua had large humid costal flatlands which are ideal to grow bananas
3-Sosua is conviniently located on the North Coast of Hispaniola island making shipping to the Noarth American market shorter and faster

In its first annual report to its stockholders for the year ended on August 31, 1900 United Fruit Company disclosed ownership of 20,000 acres of land (more than 80 millions square meters)  in the Dominican Republic of which 3300 (more than 12 millions square meters) were cultivated with a bananas plantation, we can read more about it in the second annual report to the United Fruit Company stockholders for the fiscal year ended on August 31, 1901. The book value of United Fruit Company investments (land, buildings, machinery…) in the Dominican Republic was 490'624 US$ in year 1900. One can imagine that such investment today would be roughly equivalent to a 400 or 500 millions of USD taking into consideration wage growth and GDP growth. Undoubtly United Fruit Company assets in the Dominican Republic (of which the Banana plantation of Sosua was the largest) was a huge investment even using today's standards of a globalised world with very large capital flows.

United Fruit Company: book values of its investments in the Dominican Republic (Sosua) in 1900 (click to enlarge)

The size and importance of the Sosua banana plantation  was so large that a village grew from nothing to be the third village for population in the Puerto Plata Discrict (as swhown above in a map of 1906), the plantation workers settled in the East part of Sosua Bay (Punta Payne) which we know today as “EL BATEY” ("El Batey" is how the residential area of a plantation was called in all the Caribbeans in the last century).
To protect such investment from the  political insurrections and fightings which took place in the United Fruit Company banana plantation of Sosua between the end of December 1903 and the beginning of January 1904 the company requested a milititary intervention to the US government. On January 3, 1904 the Navy steamship USS Detroit  arrived in Sosua and landed US marines in the bay of Sosua (for a full account of such episode click  here: US Marines in Sosua) .
Many people moved to Sosua  to work in the banana plantations and the region flourished: houses for the workers were built,  electricity and running water was available a small  rail road to  transport bananas from the plantations to the port of Sosua was built.

United Fruit Company bananas Plantations

United Fruit Company bananas Plantations

United Fruit Company bananas Plantations

Harvested bananas from the Sosua plantation were loaded on pack animals or tram-cars to be transported to the port in Sosua bay, there are still signs of the old railways used to carry banans from the El Choco to El Batey. Once the bananas reached the port of Sosua they were loaded to specially designed refrigerator steamships, the rest of the pier “los pilotitos” used to load the bananas on the United Fruit vessels can still be seen on the east corner of Playa Sosua.  With many vessels  travelling to and from the port of Sosua, the little town was well connected in the commercial network of the time.

Rests of the Sosua port in a picture of circa 1960 (above) and the same pier in its glory days of 1910 

The voyage from the banana plantation of Sosua to the North American fruit market in Boston took seven or eight days. United Fruit Company company had a whole fleet of refrigeration steamship s called the "Great White Fleet". Soon United Fruit Company started to use its fleet not only to ship banans. it also strated a tropical tourism trade launching the first Caribbean cruise routes.

United Fruit great white fleet

United Fruit great white fleet

Curiously a 1912 United Fruit stamship was named  “Sosua “ ( a 1185 tons vessel built in Norway),  it used to connect Port Antonio in Jamaica to New York.

steamship Sosua

The ship named "Sosua"

The Sosua banana plantation was exploited  for several years and eventually bad weather, worsening soil and water conditions and diseases caused exports to decline from 1909 untill United Fruit decided to close its Sosúa banana operations in 1916. In the following years most of the plantation workers left Sosua whose population decreased sharply. The company then sold its 26,000 acres of  land and later, in the thirties, it was bought at a fraction of its cost (for just 50'000 USD) by  the Dominican dicator Rafael Trujillo.

Rafael Truhillo

In 1938, the US President Roosevelt invited 32 governments to consult with U.S. representatives at Evian, in France  on the European Jews refugee problem.  During the  meeting in Evian in  July 1938 Trujillo’s delegate announced that the DR was ready to issue 100,000 visas to European Jews.  In October 1939, Trujillo announced that 500 refugee families would be admitted immediately,  on January 20,  1940 Trujillo offered 26,000 acres of  land he now owned  in Sosua (formely owned by United Fruit Company) to build a settlement for the first Jewish refugees to arrive .  
The American Jewish Joint Distribution Commitee  known as JDC   provided the money to buy the land from Trujillo and to start up the  Jewish refugees’ settlement of  Sosua  through the  Dominican Republic Settlement Association (DORSA).  Each refugee family received 80 acres of  land (320,000 square meters), cows, a loan, a mule and a horse.  DORSA imported experts from kibbutzim in Palestine to teach the settlers communal agriculture. They helped design and build a communal meat processing plant and butter and cheese factory.  In October 1941, the Nazis cut off Jewish emigration from the territories they occupied in Europe. Sosua’s Jewish population peaked at about 500.  After WWII many refugees left Sosua and moved to the USA and  today only a handful of Jewish families remain in town. 
The first visitors of Sosua  in the sixties and in the seventies were wealthy Dominicans: they built their ocean view vacation houses for week-end getaways from Santiago on the hill behind Playa Sosua which they called Los Cerros from the name of a wealthy neighbourhood of Santiago. International tourism development started  only later with the construction in the early 80's of the  International Airport of Puerto Plata located just 5 to 10 minutes from downtown , the growing numbers of interational tourists arriving from Europe and North America changed Sosua from a small village to  today's  worldwide renowned tourists  destination.