What word would best describe a clear and transparent water body?

The word "limpid" is the best choice to describe a clear and transparent body of water. It conveys the idea of clarity and transparency, suggesting that the water is not only clear but also possibly still and pure, allowing one to see through it easily. The term is often used in literature and descriptions of nature to evoke an image of pristine conditions.

In contrast, other options do not have the appropriate meaning related to clarity. "Inimical" refers to something that is hostile or harmful, "ineluctable" describes something inevitable or unavoidable, and "lambaste" means to criticize or reprimand harshly. None of these terms pertain to the characteristics of water, making "limpid" the most fitting choice.