The difficulty/terrain does not include the way to Tanzania itself 
but from Parking. It's a long way to go there from Dar, better have a 4WD vehicle
Selous Game Reserve is one of the largest National Parks of Tanzania. You can go there by plane (from Dar es Salaam or Zanzibar to Selous Mtemere Airstrip) or by car/bus (4WD via Kibiti - Mloka)
Selous MBega Camp is just 500m outside the park borders, so you need not enter the park to get the cache, but you should visit the park anyways.
You'll find the box near tent 1.
When you find the place empty, please give the owner the information.
Small note on cache maintenance: I'm usually 2-3 times there every year. I hold contact to the Camp owner. He is informed about the cache and can check or replace it personally within some days when I tell him.
last maintenance check: 17-Feb-2012