He stood at the rim of the canyon, looking down.

他站在峡谷的边缘，向下看。

She stood at the brim of the cliff, looking down.

她站在悬崖的边缘，向下看。

He stood at the rim of the volcano, looking down.

他站在火山口的周边，俯视着下面。

He stood at the limbus of the cliff, looking down.

他站在悬崖的边缘，向下看。

Looking down from the tall building made me feel dizzy.

从高楼上往下看让我感到头晕的。

He stood on the brink of the cliff, looking down at the ocean.

他站在悬崖的边缘，俯视着大海。

He stood on the verge of the cliff, looking down at the ocean below.

他站在悬崖边缘，向下看着下面的海洋。

Looking down from the mountain top, I felt like I was high in the clouds.

从山顶看下去，感觉自己仿佛置身于云端。

I remember looking down at my feet.

我记得低头看着我的脚。

Looking down into the distance or looking out of the window is a good option.

低头看向远方或看向窗外是一个不错的选择。