The use of composite materials in the construction of marine vessels and aircrafts is increasing and motivated by low weight advantages. These structures have to offer blast resistance, which is critical for a wide range of transportation applications. In this context, we present an investigation of the performance of composite monolithic and sandwich panels subjected to underwater impulsive loadings. A fluid-structure interaction experimental setup allows monitoring the real time deflection of composite panels exposed to blast loadings, by means of a shadow moiré technique. The performance of these panels is compared to solid and sandwich steel structures having a similar areal mass. Both non-destructive and destructive post mortem analysis are conducted to evaluate the extent and the type of damage induced by the dynamic event. This characterization is performed at different locations of the specimens and for different impulse intensities. The experimental results will be correlated to numerical predictions obtained from finite element analysis in a second presentation.