overfall
noun [ C ] geography specialized uk/ˈəʊ.və.fɔːl/ us/ˈəʊ.vɚ.fɑːl/
（由于水下的凸起或水流的交汇而形成的）异常汹涌的水域
an area of very rough water caused by a raised area in the ground under the water, or by the meeting of two currents (= movements of water in a particular direction)
The water can throw up great overfalls, which small boats should try to avoid. 水中会出现异常汹涌的水域，小船应尽量避开。
- More examples
- The overfalls are huge and very dangerous.
- The sea was white from the massive overfalls.
- With its fierce currents and overfalls, this stretch of water is difficult to sail through.
- The area is notorious for its tidal overfalls and treacherous reefs.