Subspace is often described as floating, dreamlike, or deeply focused. It is associated with the body's response to sustained sensation, adrenaline and endorphins, and with the emotional release of being held within a trusted dynamic. In deep subspace a person may have limited ability to communicate, which is one reason safewords and attentive Tops are essential.

A counterpart state, sometimes called topspace, is described by some Tops as a similar focus and altered awareness while running a scene.