Here is the situation, "she said." a man is standing up in a boat in the middle of a river, fishing.

2她举了这么一个例子：“有这样一种情况，一个男人在河中心的船上钓鱼，突然失去重心掉进了水里。”

youdao

You would not want to get off one horse and on to another in the middle of a river. Or make major changes in an activity that has already begun.

在河水中流，你是不会从一匹马下来然后又去上另一匹马的，或者，对于一件已经开始的活动，再做大的改动。

youdao

Clouds bracket the edges of the scene, but the dark blue waters of the Atlantic Ocean show in the middle, and above them, a rippling, brownish-yellow river of ash.

云层围绕着图像边缘，而在中部，大西洋深蓝色的海水映出了这股波纹状，有点像棕黄色河流的火山灰。

youdao

You would not want to get off one horse and on to another in the middle of a river.

VOA: special.2009.07.12

So there is this story about his Uncle Hoskins who takes his horse and cart with Richard in the back and drives it into the middle of the Mississippi River as a kind of practical joke on Richard.

有个故事是关于他的叔叔Hoskins的,他让理查坐在他的马车后,却连人带车掉到密西西比河里,这被作为了一个理查的真实笑话。

耶鲁公开课 - 1945年后的美国小说课程节选

Leeman was forced to hide behind a rock in the middle of the river.

VOA: special.2009.06.25

The center was in a big bleak house built in the early nineteenth century, isolated in a dip in the middle of the moors, beside a river.

NEWYORKER: She��s the One

That's how witnesses described feeling after three people slipped into the foamy waters of the Big Sioux River, in the middle of a Sioux Falls park.

CNN: March 16, 2013 -- Updated 0041 GMT (0841 HKT)

While Pakret has little to detain the traveller, it is the jumping off point for Ko Kret, a sleepy island in the middle of the Chao Praya River.

BBC: Take the boat out of Bangkok