immensity

海洋的广阔让人感到震撼。

You can feel the ___immensity of the ocean.

她意识到前方任务的艰巨性。

She realized the ___immensity of the task ahead.

站在山顶，我感受到了大自然的浩瀚。

Standing on the mountaintop, I felt the ___immensity of nature.