Brazilwood grows to about fifteen metres, dense and slow, with a heartwood that oxidises from orange to deep red. Before synthetic dyes, that was worth more than almost anything else the new colony could put on a ship. Cutting began within a generation of Cabral's arrival and did not let up for two hundred years; the species is now listed as endangered and has been nearly wiped out across most of its original range. It is Brazil's national tree, honoured by a country that very nearly finished it. The demand did not stop, either. Bow makers still consider brazilwood superior to every other material for stringed-instrument bows, so a tree cut down for the colour of its blood is now cut down for the way it flexes. Botanists moved it out of the genus Caesalpinia in 2016, giving it a name that finally matches the country's: Paubrasilia.

The park was created by decree on 20 April 1999 and covers 19,027 hectares, all of it inside the municipality of Porto Seguro. It lies between two rivers, the Frades and the Buranhém, on a coastal plain flat enough to look uninteresting from a road and cut through by deep gullies where the streams run. Most of those streams rise inside the park itself, which is the quiet argument for its existence: protect the forest and you protect the water that leaves it. A second decree in 2010 revised the boundaries. Since 2002 the park has formed part of the Central Atlantic Forest Ecological Corridor, an effort to link the surviving forest blocks of southern Bahia into something continuous. ICMBio administers it as an IUCN category II national park.

Rain falls at an average of 1,389 millimetres a year and the temperature sits around 23 degrees, which produces dense lowland rainforest and an extraordinary concentration of species found nowhere else. Seventy-one plant species here are endemic, among them Arapatiella psilophylla, Couepia belemii, Byrsonima alvimii and Manilkara multifida - names that mean nothing to most visitors and everything to a botanist, because losing this fragment would mean losing them outright. Harpy eagles hunt here and have bred in the park. More than two hundred bird species have been recorded, including the red-billed curassow, the black-headed berryeater, the ochre-marked parakeet and the Atlantic black-breasted woodpecker. Jaguar and cougar still range through it. So does the Hercules beetle, and in the forest streams the small fish Mimagoniates sylvicola and Rachoviscus graciliceps.

For most of its life the park was closed to casual visitors, a research and protection unit rather than a destination. That changed after 2018 legislation opened it to tourism, and it now receives visitors year-round, from 8.30 in the morning until four in the afternoon, by advance booking. The Trilha das Antas, the tapir trail, runs flat through the forest and is the easy introduction. The Trilha Ibirapitanga takes you up onto a suspended walkway among the canopy. The Mirante da Sede gives you the view out over the treetops, and longer trails at moderate difficulty end at waterfalls you are allowed to swim in. The booking requirement is not bureaucracy for its own sake; it is how a fragment this small absorbs attention without being worn out by it.

Not all of it is old forest. A good share of the park is regenerating ground, land cleared and worked before protection arrived and now filling back in, which is the ordinary condition of the Atlantic Forest almost everywhere it survives. Roughly 88 percent of the biome's original extent has been cleared, so the difference between old growth and recovering ground matters less here than the simple fact of cover. Walk the Antas trail and you are moving through a forest that is partly a survivor and partly a repair, with brazilwood scattered through it rather than dominant - a national tree living as a remnant inside the park that carries its name.