They trap water from one water mass inside a different water mass with different properties like temperature and salinity.

它们会将一个水团中的水困在另一个具有不同性质（如温度和盐度）的水团中。

Canada has a land and water mass of 9 970 610 km2, with a population of 30 million people.

加拿大的陆地和水域面积为 9 970 610 平方公里，人口 3000 万。

Below the Falls, the foaming water mass squeezes its way through a narrow gorge, creating the Whirlpool Rapids, which you can get to, aboard a jet raft.

在瀑布下方，白浪激流顺着狭窄的峡谷蜿蜒而下，形成漩涡急流，可让人乘坐喷射汽艇享受乘风破浪的乐趣。