Unmanned or manned underwater vehicles are often designed in cylindrical shapes which have desirable properties for withstanding the pressures that can be experienced in undersea environments. However, cylindrical designs are not required for non-pressurized enclosures. Non-cylindrical designs may provide benefits to developers including allowing a wider variety of materials for construction, greater separation between instruments or equipment, and a greater separation between the center of gravity and the center of buoyancy, which will enhance stability. The work described here proposes a bio-inspired design where novel materials are used in construction and the benefits of a non-cylindrical shape are exploited. This novel design was used to produce a human-powered submersible (Trigonus) for the 14th International Submarine Races (ISR). The design was inspired by the boxfishes (Teleostei: Ostraciidae), which have been studied extensively for their hydrodynamic properties. This family of fishes have been reported to have low-drag coefficients and enhanced stability [1 but see 2] and have inspired the design of the Mercedes-Benz Bionic concept car [3]. Additionally, the fish have relatively flat sides, which can be replicated without complicated fabrication or materials, enabling simple production with inexpensive materials. The specific species used for the design described here is the Buffalo trunkfish (Lactophrys trigonus) which has a triangular cross-section with two ventral keels and one dorsal keel. Trigonus is a human powered submersible that consists of a central frame for a modular component system with a separate hull designed to provide relatively low-drag and improved stability. The hull surrounds the frame and is attached at the ends. The hull is constructed using a novel technique where pieces of corrugated plastic are stitched together to form a triangular monocoque hull. The triangular shape of the hull mimics Lactophrys trigonus in attempt to exploit the fish's low-drag high-stability hydrodynamic properties. The monocoque constructions provides the necessary stiffness to resist deformation when underway. Preliminary testing was conducted to evaluate the performance of the submersible. Additionally, the submersible participated in 14th ISR in June of 2017. Results from preliminary testing and relative performance compared with traditional cylindrical designs are discussed.