What is another word for under surface?
Pronunciation: [ˌʌndə sˈɜːfɪs] (IPA) 
The term "under surface" can be interchanged with several synonyms, including the underside, base, bottom, underside, and the subterranean. The underside refers to the lowest or hidden part of an object. The bottom is the surface that sits on a supporting structure, while the base is the foundation of an object. The subterranean refers to being beneath the surface of the earth or ground. Depending on the context of the sentence, one of these synonyms may better convey the intended meaning. All of these synonyms are useful for those looking to add more variety to their writing or communication.
