A couple of years ago my daughter Michelle and her fiance Luke visited Ruaha National Park in southern Tanzania. They got to go on a walking safari, which at that time you could do from the camp they stayed in - Mdonya Old River.
They walked with an armed ranger from the National Park, and he showed them lots of cool stuff.
The walk lasted about 2 hours and it was a good walk, a chance to stretch the legs, which you don't get on game drives.
When they got back to camp there was a rather large elephant outside the tent!
check out this little video of the camp:
Mdonya Old River Camp, Ruaha National Park