In this study, fluid resonance in the narrow joint gaps of a caisson-type breakwater is investigated experimentally and theoretically. Particular focus is placed on the effect of the incident wave angle on the condition for the occurrence of fluid resonance and the increase of wave height in the gaps at resonance. A three-dimensional wave basin with a snake-type wave generator is used in the experiments, and the theoretical analysis is carried out using the method of matched asymptotic expansions. Then, it is found that the incident wave period and the increase of wave height in the gaps as fluid resonance occurred are independent to the incident wave angle within this experimental conditions, and can be predicted using the knowledge subject to the case that the incident wave travels perpendicular to the breakwater.
