The south-west is the Dominican Republic that tour operators forgot: a coast where the Sierra de Bahoruco drops straight into the sea, pebble beaches with rivers running across them, and almost no hotels. Barahona town itself is a working port with little to detain you; the point is the road south from it.
That road runs beneath the cliffs through San Rafael, where a cold mountain river fills pools a few metres from the surf, and on past Los Patos to Paraíso and the larimar country. Larimar — a pale blue pectolite found nowhere else on earth — is mined in the hills above Barahona, and the workings at Los Chupaderos can be visited.
At the end of everything is Bahía de las Águilas: eight kilometres of undeveloped white sand inside Jaragua National Park, reached by boat from Las Cuevas or a rough track, with no buildings, no shade and nothing to buy. It is the most beautiful beach in the country and it stays that way because getting there is awkward.
Inland, Lago Enriquillo is a hypersaline lake 40 metres below sea level — the lowest point in the Caribbean — with American crocodiles and flamingos, and Sierra de Bahoruco above it is the best birding in the country.