Spherical shell plays an important role in deep-water submersibles. This work reports the analysis and testing of spherical shells with an inner diameter of 150 mm and a wall thickness of 1 mm. Five spherical shell models are manufactured and subjected to hyperbaric pressure. By using a bridge gauge and ultrasonic thickness gauge, imperfection and thickness are measured respectively at various grid points. The shell is pressurized in steps until it is permanently collapsed. The pressure at which the shell collapses is compared to the pressure calculated based on a nonlinear buckling analysis. Analyses are performed considering both geometric and material nonlinearities. Results obtained from analysis and experiments are comparable. It is important to note that the initial imperfections have a significant impact on the buckling performance of the spheres.