To add to the many suggestions attempting to ponder the question regarding a water landing for any aircraft, and particularly a large wide body aircraft like a 777, it is worth pointing out some of the differences between ground and water impacts, much of which was covered in the AF447 thread.
When considering relatively slow speed aircraft impacts, water impacts vary from those on hard terrain in the following way. During an impact with rigid ground, the undercarriage, if deployed, absorbs a significant portion of the impact energy, with the remainder being transferred to the stiffest structural members such as the energy absorbing subfloor beams. These are generally designed to progressively collapse in order to limit to G load on the occupants. The key thing to think about here is “progressively collapse”. To give an example, drop tests on passenger sized airframes at NASA Langley Research Centre have shown how the cabin section experiences quite a pronounced deformation even for a 10m/s drop. The section progressively collapsed, as designed, and but remained intact.
For a water impact, the loading mechanisms differ significantly. The landing gear is unable to absorb the impact energy and instead the impact loads are distributed as a transient dynamic pressure load over the fuselage skin. This initial absorption by the skin momentarily slows the rate that force is applied to the structural members, and has the effect of inhibiting the buckling process to the extent that energy absorbing subfloor components become ineffective. This is why Navy helicopters are designed with additional features to improve their crashworthy response over both hard terrain and water.
In addition to the previous mechanism, the structure also experiences considerable hydraulic shock as the aircraft skin is penetrated and fluid is forced into the interior allowing large pressure forces to act directly upon the cabin floor and interior bulkheads, and as a consequence, actually increases the damage. The result is that vertical accelerations experienced by the occupants is higher due to the lack of initial buckling and rogressive collapse, compounded by the hydraulic shock effect on flooring.
In the Hudson river Airbus ditching on a smooth surface, the evidence for significant hydraulic surge is evident as can be seen from the damaged to the fuselage underside and the dislodged rear bulkhead.
http://graphics8.nytimes.com/package...9/original.pdf
http://www.aero-farm.com/museum/pa-ditch.jpg
How ditching should be done - Learmount