The cache is not at the listed coordinates. To find the cache, you must first complete adventure lab cache "Historic Swan Reach" - https://adventurelab.page.link/Bo7V
Welcome to Swan Reach. The aboriginal name for the Swan Reach area, "Kongorong" was derived from the large number of Black Swans nesting on the river and nearby lagoons. "Kongorong" is the home of the Ngarrindjeri nation. In the early 1850s, Thomas Luscombe leased 182 square miles along the Murray River, which was known as the Swan Reach Run. In 1865 a Homestead was built which is now the Swan Reach Hotel. The land was eventually broken up into smaller holdings. In 1897 Paul Hasse purchased some land and in 1900 the Blanchtown District Council approved the formation of the Swan Reach Township. Farming and fishing were the primary industries in the area. In 1898 the first punt was commissioned which was vital to residents to transport goods and produce to markets.
Once you have the bonus numbers, the cache can be found at:
S34 34.A (C-B-E) B E139 35.C D E