When my friend and I went for a swim near the mouth of the Zambezi River in
zambique, I asked a young boy,who was fishing nearby, whether there were 
sharks in the water. " No." He answered

My friend and I jumped into the water and started swimming. After several 
minutes, I called out the boy, " Are you sure there are no  sharks here?"

"No sharks." He replied. " Because sharks are afraid of crocodiles."