This much-hyped hippo sanctuary on the Black Volta River was initiated by local village chiefs in 1999. Hippos can usually be seen from November to March; once the rainy season (April to October) is underway, however, hippos disappear and the site becomes very hard to reach. Activities (C15 per person per hour) include river safaris, bird-watching, village tours and nature walks. Unless you have your own vehicle, you'll need to overnight at the sanctuary.
Accessing Wechiau is no small feat, even if you have your own vehicle. The village is located about 50km southwest of Wa, about an hour's drive; the sanctuary is then a further 20km (of bad tracks) from Wechiau. Tro-tros (minibuses) run between Wa and Wechiau (C5, 90 minutes); the Wechiau Visitor Centre can then help you hire a bicycle/motorbike/tro-tro for C15/30/50 to cover the last leg of the journey.
There's a guesthouse with very basic rooms (C20), or you can camp or even sleep on the roof. The visitor centre can also arrange homestays.
In the rainy season it's probably not worth the considerable effort to get to this remote corner of Ghana.