- The offshore petroleum industry is currently leasing and developing sites in water depths exceeding 760 m (2,500 ft). Offshore platforms designed for these sites exhibit significant nonlinear response behavior. Existing linear and second order stochastic response models and new models under development would benefit greatly from the availability of good data sets. The results from recent experimental studies focusing upon nonlinear wave runup behavior on TLPs and the nonlinear response behavior of risers are presented and discussed in terms of their statistical characteristics and probability plots. The experimental results presented illustrate the important role of wave steepness in the incident wave spectrum on the response behavior and, the influence of combined wave and vertical current shear profile on the extreme behavior observed in the experiments.