The Barton springs are surrounded by spectacular ___ landscape (nature)

The most suitable word to fill in the blank in the sentence "The Barton springs are surrounded by spectacular ___ landscape (nature)" is "natural."

The reason for this choice is that "natural" is an adjective that describes something that is related to nature. In this context, we want to convey that the landscape around Barton Springs is breathtaking and has been formed by natural processes, rather than being constructed or altered significantly by human activity.

Using "natural" helps to emphasize the beauty and authenticity of the landscape, which is an essential characteristic of areas that are geologically or ecologically significant like springs. Therefore, the complete sentence would read: "The Barton springs are surrounded by spectacular natural landscape."