B
Big_Spark
The "object" furthest away that is visible to the naked eye is our sister Galaxy, Andromeda, also known as M31 or The great Spiral in Andromeda, a Type Sbc Spiral that is about 140,000 light years across (the visible part) and lays some 2.3 Million light years from our Galaxy..which is much the same thing..in terms of distance..