Motor Matt in Brazil; Or, Under the Amazon is a juvenile adventure novel written by Stanley R. Matthews and first published in 1966. The story follows Motor Matt, a young motorist known as 'Mile-a-minute Matt,' as he embarks on a thrilling journey in a submarine named the Grampus, navigating the waters of South America and facing dangers such as a cachalot and espionage threats. This tale combines elements of adventure, mechanics, and friendship, making it a notable entry in the dime novel genre for young readers.
