The average blue whale's penis is 8 ft Accurate measurements are difficult to be made because the whale's erect length can only be observed during mating. Moreover, whales (and dolphins) have some control over their penises: they can move it and - to a certain degree - bend its tip to facilitate mating! Still, if we take into consideration the whale's size, this is like a human showing off a 10 cm penis, as the blue whale can reach 33 m (100 feet) body length.