Up the Mazaruni for Diamonds is a book by William La Varre. It depicts a search for diamonds in the isles of Guyana during the 19th century. Excerpt: "I stared at the black bank of the river whence came the weird sounds, but could see nothing. Finally, as my eyes became accustomed, I caught faint glimmers of light that seemed far inland, miles and miles, I thought. In reality the natives were no more than a quarter of a mile inland, or perhaps less. We found a landing place and, guided by the fearful din and the flickering lights, made our way through the jungle to the higher, dry ground beyond. I had all sorts of visions of great snakes dropping on me and wild jungle beasts grabbing at my heels, but nothing worse than giant mosquitoes came near."