In the first place, I want to thank Matías González Marilicán who yesterday wrote a comment about a post I published in November 2010 (Tolten River creature). Matías pointed out that a Belgian engineer who lived in that area towards the end of the nineteenth century had also mentioned that "creature". Intrigued by the commen I looked up the information and I am pleased to be able to share it with you.
So, after a long period (during which I have been exploring the early peopling of America and possible cross-cultural origins for Amerindian myths - via Phoenicians), I am once again posting about Patagonian Monsters.
The Tolten river is 230 km (143 mi) long and has its sources at Lake Villarica at 230 m (754 ft.) above sea level. It crosses the Chilean province of Cautín in Araucania with an East - West course and flows into the Pacific Ocean.
Verniory and the "Great Best"
Gustave Marie Eugene Verniory (1865 - 1949) was a Belgian engineer who wrote a book ("Ten years in Araucania, 1889 - 1899) describing his experiences in central -southern Chile, during the period when he worked for the Chilean government building a railway between Victoria and Toltén, and later, from Temuco to Pitrufquén
Verniory learnt the Mapuche language (mapudungun) and lived in Lautaro, Temuco, Angol and Pitrufquén. He left Chile in 1899 and never returned.
His book (apart from trains and railway building) deals with his daily life with the locals, the Mapuche natives and the European settlers. As well as his interaction with the forests and the Patagonian environment. As a typical Victorian European, he was also a hunter and besides hunting avutardas (a local variety of ibis), he sought other trophies. It is in this context that he wrote:
"We had, for a brief period of time, the hope of hunting something extraordinary.
Some persons have seen it several times, a league [5 km - 3.1 mi.] more or less, from here on the shore of our river: a fabulous monster which they have named the "gran bestia". [in Spanish in the original French text. "Gran Bestia" means "Great Best"] Its description varies according to the witness. Some have seen it dragging itself across the pebbles, others, leaving the water. Its size ranges from two to ten meters according to the differing statemens [6 - 33 ft.] The only point that they all agree upon is that its body is large, black and shiny. It has created a myth among the simple people; the monster has already devoured many men and fear is spreading.
We organized many expeditions to find it, but we were not successful. We will never find out what the great beast is. I am inclined to believe that it is one of those enormous seals, of the kind I saw at the mouth of the Imperial Rvier, which, has gone up-stream and, once its vacations were over, returned to the sea." 
The Imperial River he mentions, was where he spent his summer holidays in February de 1897. The hunting expeditions took place during August 1897.
This creature lived close to the town of Pitrufquén (which is in the middle of the map, above).
I share Verniory's opinion and it is likely that the beast was a Sea Wolf (Otaria flavescens) which in those days lived along the Araucanian coast or, a Sea Lion (Otaria leonina) which still lives along the Chilean coast. Perhaps one of these animals swam up-river following their prey.
It could also be some other kind of seal, an extinct species of fresh water (or sea) seal. Because, the size of the creature is quite large (over 2 meters long - 6 ft.) which means it would have been a very big seal.
Once again I thank Matias for the tip.
 Gustave Veriniory, Diez años en Araucania, 1889 - 1899. pp 456
Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2014 by Austin Whittall ©