Cylindrical Aquarium Tunnel Tunnels are typically cylindrical in design. The most common tunnel has a constant radius and spans 180°. These tunnels can be faceted to make turns within the tank. The ideal tunnel has the viewer at some point completely surrounded by water so that in whatever direction they look, they only see water. A tunnel design can and many times does span beyond 180° to provide the viewer with a panoramic view of the tank interior. This type of design requires some unique coordination regarding the installation.
Optimized Aquarium Tunnel There is an option other than the cylindrical design when designing tunnels. Since the water pressure at the top of the tunnel is less than the water pressure at the bottom, the acrylic window designer can take advantage of the differential and provide an optimized tunnel profile that is more elliptical in shape. When the width of the tunnel gets wide and the shape is cylindrical, the top of the tunnel starts getting quite high. If the top of the tunnel is too far above the heads of the people in the tunnel, then the feeling of being underwater starts to be lost. Optimizing the tunnel brings the top of the tunnel closer to the people in the tunnel, returning that intimate underwater feel. Properly designed, the optimized tunnel shape can lower the stress and movement of the acrylic tunnel; thus, the design thickness can be reduced, providing a cost savings as well better aesthetics. The optimized design works best for tunnel profiles that are very wide where the water is not too high above the top of the acrylic. Optimized tunnel sections are specific to the width and depth of the tunnel. The optimized tunnel can be worked into numerous aquatic environments and its design naturally varies on width and depth. However this type of design works best in a wide aquarium space and just below the surface of the water.
Rectangular Aquarium Tunnel Tunnels can be made in a rectangular shape. This is an expensive option because the acrylic needs to be thicker than with the cylindrical or optimized design options since the tensile stresses tend to be quite high. The rectangular shape also offers the poorest view. Unlike the curved tunnel designs which offer uninterrupted views, the flat panel tunnels have a disjointed view since the animals must swim past the corners of the acrylic panels that are on different planes. Because of these disadvantages, rectangular tunnels are not the choice of architects designing aquaria.