Thermohaline circulation is a foundational concept in introductory and advanced undergraduate oceanography courses which describes the density-driven flow of water throughout the world's oceans. This concept is commonly taught using two-dimensional (2D) diagrams and graphics. However, students often struggle with the three-dimensional (3D) patterns and connections associated with thermohaline circulation. To remedy this, we sought to present thermohaline circulation in three dimensions to enable students to apply their knowledge and work with physical models. We constructed an interactive physical model of thermohaline circulation which included 3D printed continents and Arduino-controlled LED strips colored to represent global temperature and salinity patterns. We implemented the model as a teaching tool in a large undergraduate introductory oceanography course during the module covering thermohaline circulation. In discussion sections, students utilized the model to observe patterns, match depth profiles of real data to different geographic locations, and apply their knowledge to draw their own depth profiles using the model. After completing the in-class assignment, we assessed whether the model helped students understand and apply key concepts from lecture using both student worksheet responses and self-assessment surveys. Student scores increased significantly after using the model, and self-assessment data suggested students enjoyed using the model as well. The model is broadly applicable to a variety of settings, including other undergraduate courses, K-12 outreach, and public engagement to support oceanographic learning across a range of levels.