Would it be possible for a plane to crash into the ocean without major damage? I'm not too clued up in terms of physics or aviation, so it's a genuine question.
Like Exiledintheusa said, you'd need a lot of things to go right.
If the pilots have control and are planning to ditch the plane, if they can glide down and maintain control all the way down to the water, you can suffer less damage and people can survive. So in the case of engine failure, for example, you can make a water ditching but of course it's tremendously difficult to maintain control. US Airways Flight 1549 was a successful ditching but that was in the Hudson River. Ethiopian 961 was an attempted ditching off the Comoros but because the pilot was fighting off hijackers, he couldn't keep the plane level and it banked left and an engine/wing got caught in a reef and the plane broke apart though there were survivors.
On the other hand, if the pilots don't have control (stall, catastrophic structural damage, etc), then the plane would hit the water at very high speed and there will be massive destruction.