This study aims to explore the mental models of students about suspending objects in liquid fluid. The study used a descriptive qualitative method and implemented cross-sectional approach. It involved 57 students from grade 5 of elementary school to fourth-year prospective physics teachers. The data collection used a test consisting of twenty-six essay and four multiple-choice items, which covered several contexts and factors. The data were analyzed by adapted phenomenographic procedures and integrated with some stages of thematic analysis. The types of mental models that were successfully explored include the density-, mass-, weight-, volume-, and gravity-based model, leaked boat model, air as a floater model, etc. The predominant students' mental model was the initial one, followed by the synthetic and scientific level, respectively, and the adopted mental models tended to form a hierarchy based on the grade of students. The results showed that the suspending models tended to be adopted and was influenced by the mental model in the floating and sinking contexts. This result confirms the findings of previous studies, which stated that mental models depend on the context of the phenomenon being presented. The existence of variations in the students' mental models for reasoning about density and depiction of suspending objects revealed gaps in the consolidation of their mental models. In learning activities, it is not enough to teach the concepts of floating and sinking. Hence, an adequate portion for the suspending concept must be provided by depicting various object positions and emphasizing a more conceptual of density-based model. [Note: The page range (257-287) shown on the PDF is incorrect. The correct page range is 253-283.]