“Clash of the Titans” was widely panned by critics, and heavily criticized for the poor use of post-processed 3D, but the CG was actually quite well-done.  CGNews has some details from MPC on the creation of the final sequence with the Kraken.

For the final sequence, MPC created the Kraken and a CG ocean. To achieve a fully realistic fluid animation over 20 passes of water were used, combining volumetric rendering for water particles and mesh rendering for the water surface. All fluids were done using Flowline and rendered through RenderMan. MPC also created the FX for the ‘rockifying’ Kraken. To achieve the shattering effect, MPC used proprietary software PAPI.

via MPC Play War With Clash of The Titans | CGnews.