sometimes diving to depths of forty meters to reach them. 有时它们潜到40米深

257. the greatest concentration to be found anywhere on Earth.
     到处都是世界上最伟大的聚集
258. The humpbacks have finally arrived.
     座头鲸终于抵达
259. The giant shearwater flocks hunt the krill swarms
     庞大的水雉鸟群大量捕食磷虾
260. sometimes diving to depths of forty meters to reach them.
     有时它们潜到40米深
261. A large humpback eats three tons of krill a day.
     一头成年座头鲸每天能吃掉3吨磷虾
262. The polar seas in summer are the most productive on the planet
     夏季的极地海域是地球上最多产的
263. and the whales gorge themselves round the clock.
     鲸鱼昼夜不停地在此进食

来自《行星地球 第一季 第九集 Planet Earth S01E09 海洋》第 260 行