Helena Bonham Carter narrates this BBC Earth Imax documentary, but the stars are isolated gecko-like desert lizards, vivid pink flamingos by the thousands, schools of mud-bathing elephants and nasty crocodiles that snap at thirsty wildebeests. And above all, the water. The 3-D guide to the continent’s rushing rivers, bone-dry droughts and drenching seasonal rains showcases the primal importance of water to flora, fauna and filmmakers. Emmy-winning directors Patrick Morris, Neil Nightingale and Mike Slee submerge their cameras in the Red Sea to capture views of stunning coral gardens, skim them across gigantic Victoria Falls and fly them 19,000 feet over stratospheric snow-capped Kenyan mountains. It shows the continent as a land of two seasons, wet and dry. Each shift of the cycle challenges life or nourishes it. The 40-minute program this week begins a yearlong run at the Minnesota Zoo’s Imax theater. (12000 Zoo Blvd., Apple Valley; 952-431-4629.)