Sumba occupies a peculiar position in Indonesian geography and biology. Part of the Lesser Sunda chain in the province of East Nusa Tenggara, it sits south of Flores and west of Timor, isolated enough that its flora and fauna evolved along separate paths from its neighbors. The result is an island with an unusually high proportion of endemic species -- organisms that exist here and nowhere else on Earth. Manupeu Tanah Daru protects the largest remaining tract of lowland forest on Sumba, a habitat type that has been shrinking steadily as the island's population grows and agriculture expands. The park's terrain is steep and rugged, cut by rivers that carve deep valleys through the limestone before spilling over cliffs in spectacular waterfalls. The most famous of these, Lapopu, drops roughly 90 meters in a multi-tiered cascade that visitors reach after trekking through dense forest -- a journey that doubles as an introduction to the park's extraordinary biodiversity.

Seven bird taxa are endemic to Sumba, and Manupeu Tanah Daru shelters all of them. The yellow-crested cockatoo -- the Sumba subspecies, with its lemon-colored crest and ear-splitting call -- is critically endangered, its numbers diminished by decades of capture for the pet trade. The Sumba green pigeon moves through the canopy in flocks, feeding on fruit with a quiet efficiency that makes it easy to overlook until a shaft of light catches its iridescent plumage. The Sumba flycatcher, the Sumba cicadabird, and the apricot-breasted sunbird round out a list that reads like a birder's fever dream. In total, 87 bird species receive protection within the park's boundaries. But it is the hornbill that draws the most attention -- partly for its size, partly for its rarity, and partly because watching one fly overhead, its wingbeats audible from a hundred meters away, is the kind of experience that rearranges your sense of what a forest can contain.

Birds get the headlines, but the butterflies of Manupeu Tanah Daru are equally remarkable. Fifty-seven species are protected within the park, and seven of those are endemic to Sumba. Papilio neumoegenii, a swallowtail with dark wings marked by pale crescents, is one of the most sought-after by collectors -- which is precisely why it needs a national park. The delicate Delias fasciata, with its red and white underwings, flickers through forest clearings like a living flame. Ideopsis oberthurii, Junonia adulatrix, Athyma karita, Sumalia chilo, and Elimnia amoena complete the endemic roster, each adapted to the specific conditions of Sumba's forests -- the humidity, the altitude, the particular mix of flowering plants that sustain them. These are not charismatic megafauna. They will never appear on a tourism poster. But their existence in a single place, found nowhere else, makes this park a conservation site of global significance.

About 118 plant species are protected within Manupeu Tanah Daru, forming the foundation on which everything else depends. Toona sureni, a valuable timber tree, grows alongside the pungent Sterculia foetida -- whose name warns of its smell -- and the lac-producing Schleichera oleosa. Tamarind and candlenut trees provide food for both wildlife and the local communities that border the park. Casuarina species, with their needle-like leaves, stabilize slopes and riverbanks. Invasive Lantana camara, an aggressive shrub from the Americas that has colonized disturbed areas throughout the tropics, poses an ongoing management challenge. Beyond the cataloged species, the forest floor supports medicinal herbs used by Sumbanese communities for generations, and rare orchids cling to the trunks of canopy trees in the park's more humid valleys. Long-tailed macaques swing through the mid-story, and Timor deer -- introduced but now well established -- move through the undergrowth at dawn and dusk.

The park's rivers do not merely drain the landscape; in Sumbanese culture, they carry spiritual significance. Matayangu Waterfall, which plunges roughly 100 meters over unusual rock formations deep in the park's interior, is considered a sacred site -- a place where ancestors dwell. Reaching it requires a trek through savanna and forest that can take hours, a journey that filters out casual visitors and rewards those who persist with a cascade of extraordinary power and beauty. Lapopu Waterfall, more accessible and better known, offers a 90-meter stair-step descent surrounded by forest so dense the sunlight arrives green-filtered and softened. These waterfalls are not tourist attractions in the conventional sense. There are no handrails, no gift shops, no interpretive signs. They are pieces of a landscape that remains, in many stretches, as wild and unmediated as anything in Indonesia -- which is exactly what makes Manupeu Tanah Daru worth protecting.