Heavyweights of Africa!

Chris and Martin set out across the African savannah to find one of the creature world's true heavyweights, the rhino. They see a herd across a river but when they try to cross, they find the river fiercely protected by crocodiles and another African heavyweight, the hippopotamus. How are they going to get across? Allison, Martin and Chris get busy solving the problem so we can all meet the rhino!