The Arctic Circle, a frozen ocean ringed by three continents.
北极圈，一片被三个大洲环绕的冰冻的大洋。
Survival here is a constant battle against the planet's most ferocious elements.
求生于此是一场面对全球最恶劣气候的持久战。
One third of the Arctic Ocean is covered in ice all year round and for half a year the sun does not rise above the horizon.
北冰洋三分之一的洋面终年被冰所覆盖，而有半年的时间太阳都不会在地平线上升起。
But in summer, the sun never sets.
不过在夏季，太阳却永不下落。
Thousands of animals head north to reap their field as the shallow seas of the Arctic Circle become some of the richest on earth.
成千上万的动物涌向北极，分享那里的饕餮盛宴，而此时北极圈内的浅海区成为了全球最富饶的地区之一。
In winter, the Arctic Ocean is almost completely covered in ice.
冬季里北冰洋几乎完全被冰所覆盖。
The sea ice grows to encase the northern tips of Asia, Europe, North America, and several islands.
海冰的扩张使亚洲欧洲和北美洲的北端以及一些岛屿全都被冰封锁。
This is one of the most hostile habitats on earth, but the planet's most resilient animals survive above and below the ice.
这是全球环境最恶略的栖息地之一，然而地球上适应力最强的动物们却在冰面上下生存着。
Thousands of whales migrate across the Arctic Ocean search for food.
几千头鲸迁徙经过北冰洋寻找食物。
Seals nurse their young and compete for females. And it's home to around twenty thousand polar bears.
海豹们照料着幼崽，并且为求偶而竞争。这里还生活着大约两万头北极熊。
On the Norwegian island chain of Svalbard, there are more polar bears than people.
在挪威的斯瓦尔巴德群岛，北极熊的数量比当地人口还多。
Svalbard lies entirely within the Arctic Circle, just one thousand kilometers south of the North Pole.
斯瓦尔巴德群岛完全在北极圈之内，距离北极点仅有一千公里。
From October to February, the sun does not rise above the horizon, and for three and half month each year, Svalbard is enveloped in darkness.
从十月到次年二月，太阳都不会在地平线上升起，而每年有三个半月时间斯瓦尔巴德群岛都被完全笼罩在黑暗中。
Pregnant polar bears hibernate through the long dark winter.
怀孕的母北极熊会在漫长而黑暗的冬季进行冬眠。
In a den on the slopes overlooking the sea ice, this bear has just given birth to twins.
在坡上一处可以俯瞰海冰的洞穴里这头母熊刚刚生育了一对双胞胎。
The cubs are born blind and deaf but instinct drives them to find their mother's milk.
初生的小熊即瞎又聋但本能使它们摸索着喝到母亲乳汁。
The milk is one third fat. On this rich diet, the cubs will grow rapidly.
母乳中有三分之一是脂肪，靠着这营养丰富的膳食，幼崽们会迅速成长。