Editor’s Note: Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, together with the solutions. Rolex’s Perpetual Planet Initiative has partnered with CNN to drive awareness and education around key sustainability issues and to inspire positive action. CNN  —  Transporting the world’s second largest land mammal halfway across the second largest continent isn’t exactly easy. But in a 3,400-kilometer (2,100-mile) journey that involved