Saut-d'Eau answers, better than any argument, the question that surveys of Haitian religion keep getting wrong.
What happens. In mid-July, for the feast of Our Lady of Mount Carmel, tens of thousands of people converge on the falls on the Tombe river near Ville-Bonheur. They attend mass. They also bathe under the waterfall, tie strips of cloth and offerings in the surrounding trees, and leave the clothes they arrived in behind in the water, walking out in new ones. The place belongs to Ezili, and to Danbala and Ayida Wedo, the serpent and the rainbow, whose presence is read in the falling water itself.
The pilgrims are not doing two things. They are doing one thing, and would not recognise the distinction an outside observer wants to draw between the Catholic half and the Vodou half.
The origin story carries the same point. Tradition holds that the Virgin appeared in a palm tree at Ville-Bonheur in the middle of the nineteenth century; that a priest, alarmed at what was developing, had the tree cut down; and that the pilgrimage continued anyway and grew. Whatever happened, the story is told as one in which official disapproval simply failed to be relevant.
Why this matters for every number you will read. Estimates of how many Haitians practise Vodou range from a small minority to a large majority, and the range is not caused by bad data collection. It is caused by the question. A census or survey asks people to select a religion, and a Haitian who serves the lwa and is a baptised Catholic will generally answer Catholic: accurately, by their own understanding, since the proverb holds that one must be a good Catholic to serve the spirits. The instrument assumes an exclusivity the practice does not have, so the figures measure how people answer forms rather than what they do. Saut-d'Eau in July is what the practice looks like.
The hostility has been real and it has not worked. The Catholic anti-superstition campaign of 1941-42 destroyed temples and ritual objects with government backing; Haitian law penalised superstitious practices for much of the country's independent history; Vodou was given official recognition only in 2003. Rapid Protestant growth has since produced a body of Haitians who explicitly reject the tradition, and during the cholera epidemic after the 2010 earthquake, dozens of people, mostly priests and priestesses, were lynched by mobs blaming them for a disease introduced by United Nations peacekeepers.
The pilgrimage has outlasted all of it, and it takes place this July as it did last.