The park covers roughly 3,040 hectares on the southern side of Samborombón Bay, a place where the endless grass of the Pampas finally runs into the Atlantic. There are no mountains here, no waterfalls, nothing to make a calendar. There is only the subtle drama of a wetland: open plains shading into coastal beach, stands of low woodland, and the silver sheen of brackish water threading through it all. A designated Ramsar wetland of international importance, it is the kind of landscape that rewards patience over spectacle, where the interest lies not in the view but in what the view contains.

The pampas deer, venado de las pampas, is the park's whole reason for being. It is a medium-sized, fawn-colored cervid built for grassland, and it is in danger of disappearing from Argentina. The Samborombón population has been shrinking for decades at roughly four percent a year, worn down by feral dogs and wild pigs, by poaching, by the slow conversion of its habitat into pasture. Conservationists count the animals carefully, because every count matters when the total is this low. The park's job is brutally simple and genuinely hard: hold the line, keep the grassland intact, and give a vanishing species somewhere it is allowed to stay.

The deer share their refuge with a full cast of pampas wildlife. Capybaras, the world's largest rodents, graze the wet margins. Crab-eating foxes trot the tree lines, and small wildcats hunt the grass. Overhead and underfoot, more than a hundred bird species pass through, among them the rhea, the great flightless runner of the South American plains, and the crested caracara, a bold raptor that walks as often as it flies. The bay's shallows draw clouds of waterbirds. There are venomous snakes here too, including the yarará, and small frogs and toads in the seasonal pools. It is, in miniature, the whole living machinery of the Pampas, preserved because one animal needed it preserved.

Campos del Tuyú asks something unusual of admirers: stay back. The park does not allow recreational visitors, and as of early 2025 general entry remained closed. The land is fragile and the deer are skittish, and the calculus favors the animals over the audience. The only way in is a guided tour to Punta Rasa, typically departing from nearby San Clemente del Tuyú, rolling through a slice of the park in four-wheel-drive trucks because the sandy tracks wash out with every tide. It is a place protected partly by its own inaccessibility, a wilderness whose greatest gift to the species it shelters is to be left, mostly, alone.