A modern Spanish writer gives the following solution of a
popular tradition that a whale was once seen making its way up the
Manzanáres. The Manzanáres is a singularly shallow river, at certain
times of the year not half covering its bed, which rendered the
tradition still more marvellous [75].
The solution is this: "A wine-merchant living on its banks was once
unfortunate enough to have an accident in his storehouse or cellar,
by which a number of wine-skins were sent floating down the stream. The
wine-merchant ran along the bank, calling on the neighbours to arrest
the float, the rather that one of the skins was full of wine; and as
the danger of losing them increased, he went on crying frantically,
"Una va llena!" ("One of them is full!")
Now Spaniards make but a scarcely perceptible difference between the
sound of b and v, so that his cry sounded in the people's ears like
una ballena, which would have meant a whale!