..but less than 1% will make it. 但只有不到1%能成功登顶

177. This is the equivalent of a human being scaling a waterfall
     相当于人类去攀登
178. over a mile high.
     近两公里高的瀑布
179. Millions attempt the climb...
     数以百万计的虾虎鱼向顶端进发
180. ..but less than 1% will make it.
     但只有不到1%能成功登顶
181. This goby has been climbing for days.
     这只虾虎鱼已经爬了好几天了
182. Made it!
     成功了
183. Those that reach the top can now prepare to breed.
     抵达瀑布顶端的虾虎鱼现在可以准备繁殖了

来自《行星地球 第三季 第四集 Planet Earth S03E04 淡水》第 180 行