Which of the following is indicated as not being a lake?

A pond is categorized as a body of water similar to a lake, typically smaller and shallower than a lake, but it's still considered a type of standing water. The distinction lies in the size and depth, rather than completely being a different type of water body.

In contrast, a river is a flowing body of water, a stream is even smaller and also flows, while an ocean is a vast body of saltwater that makes up a significant portion of the Earth's surface. These options highlight different characteristics of water bodies, where lakes and ponds share more similarities than differences. Therefore, the other options listed do not represent standing bodies of water like lakes or ponds do.