Mini Underwater Glider (MUG) is an effective and low-cost educational platform for undergraduate student and other inquisitive people in marine systems and underwater robots. Simple but innovative design of MUG could be made by hand tools with ordinary components available in general stores and very low cost. Therefore, it can be used for not only education purposes, but also the markets of toys and scientific models to inspire youth with regards to marine science and engineering. This paper introduces all the aspects of MUG, including design goals, operation principle, mechanical structure, motion analysis, and underwater tests. The experimental results showed a high performance of MUG’s glide.