You can get to Bahía Negra by air, road or river.
SETAM flights from Asunción to Bahía Negra on Wednesdays. The return ticket cost GS.580,000. The plane departs the Aeropuerto Militar (military airbase) which is next to the Silvio Pettirosi airport at 7:00AM and make stopovers at Concepción, Puerto Casado, Vallemí, Carmelo Peralta, and Fuerte Olimpo before reaching Bahía Negra around 11:00AM.
Stel Turismo runs one weekly bus from Asunción, the bus ticket cost GS.200,000. The bus leaves Asunción every Thursday at 7:00PM and travelling time vary between 20-24 hr according to road conditions. The same bus returns from Bahía Negra to Asunción on Saturdays at 8:00AM.
Bahía Negra is 823 km by road from Asunción. You travel northwest along the Transchaco highway for 415 km up to Cruce Los Pioneros, then north on an unpaved route for 408 km. Travelling time by car should be between 16-21 hr, depending on road conditions. The unpaved road may be closed to traffic when there are heavy rains.
A pleasant, though slow, way to arrive to Bahía Negra is aboard the Aquidabán boat from Concepción. The boat travels once a week and Bahía Negra is its last port of call. The boat journey takes 4 days and it's not a touristic boat, it's a cargo one, so the boat stops at every port along its way, loading and unloading cargo and passengers. Departure days vary so check before with the port authorities for the latest schedules. Boat ticket costs GS.100,000