Spanish television broadcast amateur video footage of surprised bathers at the Sunday landing at sun-splashed Canos de Meca beach in Cadiz province.
The migrants included four babies, including one just 11 days old. A group of bathers was shown gathered around one of the infants, gently counting the fingers on one of its hands and coming up with six.
Bathers helped emergency medical crews carry some of the undocumented foreigners on stretchers to ambulances for treatment for dehydration, hypothermia and malnutrition.
One African screamed wildly into a cell phone and ran around as colleagues tried to restrain him. It was no immediately known where the African's were from.
Such arrivals are common in Spain, especially in summer, but usually take place under cover of night, not on a beach packed with weekend sunbathers.
Each year tens of thousands of Africans seeking to escape poverty attempt treacherous trips in flimsy, overcrowded boats, hoping to reach Spanish soil by crossing the Strait of Gibraltar from Morocco or heading west to the Canary Islands.
Many are caught and sent back, though thousands manage to slip through.
A Moroccan immigrant workers' association known as ATIME says some 4,000 migrants have drowned in the past five years while trying to make such trips.