Just 10 metres beneath the ice, 就在离冰面10米以下的海底上

139. a permanent hole in the sea ice, kept open throughout the winter by strong ocean currents.
     冰间湖是结冰的海洋上永久性的洞孔 因为有强大的洋流使它们冬天也不会冰封
140. This unusual duck pond provides an overnight sanctuary
     这个不同寻常的水池是过夜的庇护所
141. and, when day breaks, a rare chance to feed.
     而且到了白天还有难得的进食机会
142. Just 10 metres beneath the ice,
     就在离冰面10米以下的海底上
143. the sea floor is carpeted with dense mussel beds.
     布满了密密麻麻的贻贝
144. These can only be reached during a brief lull in the currents.
     这个地方只有在洋流暂时停歇时才能吃到
145. The ducks must quickly prise the mussels free before the tide starts to turn.
     绒鸭必须赶在潮流转向之前迅速采食

来自《行星地球 第一季 第六集 Planet Earth S01E06 冰雪世界》第 142 行