Water-driven debris generated during tsunamis and hurricanes can impose substantial impact forces on structures that are often not designed for such loads. This paper presents the design and results of an experimental and analytical program to quantify these potential impact forces. Two types of prototypical debris are considered: a wood log and a shipping container. Full-scale impact tests at Lehigh University (LU) were carried out with a wooden utility pole and a shipping container. The tests were carried out in-air. The purpose of these tests was to provide baseline, full-scale results. Because of size limitations, a 1:5 scale shipping container model was used for in-water tests in the Oregon State University (OSU) large wave flume. These tests were used to quantify the effect of the fluid on the impact forces. Results from both experimental programs are presented and compared with analytical predictions. The predictions are found to be in sufficient agreement such that they can be used for design. A fundamental finding is that the impact forces are dominated by the structural impact, with a secondary effect provided by the fluid. Both forces are quantified in the paper.