The Sahara is the biggest desert on the globe.
撒哈拉是全球最大的沙漠。
It is the size of the United States, and its arid interior can unleash the mightiest sandstorms on the planet.
其面积堪比美国，从它干旱的内陆可释放出地球上最强势的沙尘暴。
Ferocious winds whip up billions of tiny sand grains into massive walls.
猛烈的狂风卷起成万上亿颗细小的沙粒形成一堵巨大的沙墙。
Reaching more than 5,000 metres into the air, ten times the height of the Empire State Building, covering areas the size of Britain.
五千米高的沙墙拔地而起，其高度是帝国大厦的十倍，其面积足以覆盖大不列颠。
Battling through this sandstorm in Mali is 16-year-old Mamadou.
一名16岁的男童玛玛杜在马里的沙尘暴中挣扎求生。
He's a cattle herder who left home three days ago on a mission to find water for his cows.
他是一个牧牛人，三天前离开家，踏上为牛寻水的征途。
It's a huge responsibility on his teenage shoulders.
他稚幼的双肩扛起了无比艰巨的责任。
He must endure the fury of the desert alone, but there's an even bigger challenge ahead.
他必须独自忍受沙漠的盛怒，但前方，更大的挑战在等着他。
He's in a race against the biggest land animal on earth -- African elephants.
他在与地球上最大的陆地动物赛跑--非洲象。
This desert herd is also desperate for water because Mali is gripped by drought.
它们同样渴望得到水的滋润，因为全马里都深陷干旱的魔爪。
It's 40 degrees Celsius. Most of the water holes are already dry.
这里有40摄氏度。大部分水坑均已干涸。
Only one place for 80 kilometres will still have water -- Lake Banzena.
只有80公里外的一个地方仍会有水--斑泽纳湖。
And this is where both the elephants and Mamadou are heading.
这里就是非洲象和玛玛杜的目的地。
If Mamadou keeps up a fast pace, he'll reach the lake by morning.
如果玛玛杜保持快速行进，他就会在天亮时分到达湖边。

But only 50 kilometres behind him are the greatest nomads of the desert.
但就在他身后50公里的地方，沙漠族群中最大的游牧族也在蠢蠢欲动。
Elephant matriarchs guide the herd, following an incredible mental map of all the water holes to be found in an area of tens of thousands of square kilometres.
母象族长带领着象群，循着方圆几百几千公里内由诸多水坑标记的奇妙记忆地图，向湖边进发。
Acacia trees give them just enough fuel to keep walking, but they can't rest, day or night.
刺槐树为它们的旅途提供了充足的供给，但它们不能停息，必须日夜行进。
But, for Mamadou, nightfall means he has no choice but to stop.
但是对于玛玛杜来说，黑夜令他别无选择，只能停歇。
Meeting elephants in the dark could be fatal.
在黑暗中遇上象群是致命的。
A hurried breakfast is the little precious milk Mamadou can get from his cows.
玛玛杜从奶牛那挤出几丝珍贵的牛奶，凑成了一顿匆忙的早餐。
It keeps him one step away from dehydration. But he's got to get going.
这可以暂时防止他脱水。但他必须得前进了。
The elephant herd have walked through the night, making up ground.
象群走了一夜，渐渐逼近。
Finally the end is in sight for Mamadou. But he walks straight into trouble.
终于，湖水映入了玛玛杜的眼帘。但麻烦正等着他。
Not only have the massive elephant herd beaten him to the lake, but they're also blocking his access to the water.
庞大的象群不仅先他一步到达湖边，还堵住了他前进寻水的道路。
Mamadou knows the elephants could charge, so he is careful not to get too close.
玛玛杜深知万象奔腾的威力，所以他很小心，不过于接近象群。
It's an uneasy truce while he works out how to break through.
冲突一触即发，同时他还要想出突破重围的办法。
Suddenly an elephant charges his cows.
突然间，一头大象向他的牛群冲去。
Mamadou fights back, but armed only with sticks, it's a battle of David and Goliath.
玛玛杜给予了反击，但他只有树枝可用，这简直就是大卫和歌利亚之间的战斗。
Mamadou's courage has managed to shift over 50 elephants.
玛玛杜鼓起勇气赶走了五十多头大象。
Luckily, conflicts like this are very rare.
幸运的是，这样的情况极少。
Finally Mamadou drives his cattle towards the life-giving water.
终于，玛玛杜赶着他的牛群走向这生命之水。
The elephants move off and find their own part of the lake.
象群离开，去寻找这片湖中自己的领域。
At last, they too have an opportunity to drink... and even play.
最终，它们也饮上了水，甚至玩耍起来。
It will be two months before there's any chance of rain replenishing the water holes, so Mamadou's struggles will go on.
两个月内将没有雨水填满那些水坑，所以玛玛杜还得继续奋斗。
But in one part of the desert, a shrinking water supply leads to a surprising opportunity.
但在沙漠的一隅，水源的吃紧却带来了意外之喜。