The present paper studies the dynamics of submerged expanded elastic tubes due to postexpansion sudden mandrel release known as pop-out phenomenon. A mathematical model describing the dynamics of the borehole-fluid-tube system is presented. Coupling of the fluid-structure interaction and damping effects were taken into consideration. An analytical solution for the displacement, stress, and pressure wave propagation in the fluid-tube system was obtained. The developed model predicted localized critical regions where the structure might experience failure.