Mariner’s Island is an eight- story commercial office building built in the shape of an offset trapezoid. The structure is supported on precast driven piles and is nearly surrounded by a natural waterway. The structural system consists of post-tensioned concrete slabs, precast prestressed beams, and a cast-in-place lateral resisting system. Coupled with the extensive use of precast concrete, including the striking exterior facade, this project was awarded the Precast Institute Award for Precast Concrete Design. This structure, located in Foster City a few miles south of San Francisco, experienced the dynamic effects of the Loma Prieta earthquake. Post-event observations indicated no structural damage despite its location or the soft underlying soils.