Soon we had left the river estuary and were heading towards the open sea.

不久我们就离开了河口，驶向辽阔的大海。

youdao

On basis of location, water dynamic, nutrient loading, red tides are classified as six types of estuary type, bay type, culture zone, coastal water type, upwelling type and open sea.

根据赤潮灾害发生的空间位置、水动力、 营养物质来源等因素，将赤潮灾害类型划分为河口型、海湾型、养殖型、沿岸流型、上升流型和外海型六类。

youdao

After the wide-open water of the estuary, the mangrove forest feels eerie and magical.

BBC: Relaxing among the Yucatan's flamingos