Unmanned underwater vehicles (UUVs) have received worldwide attention and been widely used in various applications. In this paper, a recently developed low cost UUV prototype at the University of Canterbury is introduced, which is designed specifically for shallow water tasks, especially for inspecting and cleaning sea chests of ships for bio-security purpose. The main hull of the UUV is made of polyvinyl chloride (PVC), with a 400 mm diameter and 800 mm length. External frames mount two horizontal propellers, four vertical thrusters and power is derived from onboard batteries. The maximum thrust force of up to 10 kg that is provided by the propellers can generate a forward/backward speed of up to 1.4 m/s for the 112 kg UUV. The vertical thrusters provide depth control with a max thrust force of 20 kg. The UUV is equipped with a range of sensors capable of sensing its instantaneous temperature, depth, attitude and surrounding environment. Costing less than US$10,000 for a prototype, it provides an excellent platform for further underwater vehicle development targeting shallow water tasks with a working depth up to 20m.