If the plane were to crash into the ocean, you would most likely die from impact with the water.
Most pilots dont like that option.
They will do their best to try and "ditch" the plane into the ocean, which will give them half a chance of survival. Ditching means they will try and land the plane in the ocean. They will hope to land upright and not be tripped up by the waves, which can happen. The plane can be broken up if they hit the water at the wrong point of the wave... which they will endeavour to avoid!
A friend of mine survived a small aircraft that ditched into the sea several miles offshore from Vila. The plane stayed afloat long enough for everyone to get out.
But most of the passengers did not have their life jackets with them from the plane. Some took off the clothing they had on as they felt they couldnt swim with their clothing. Coldness, exhaustion, fear, loosing track of some of the passengers affected the survivors. The group of 4 clung to one jacket and swam towards a small light, encouraging each other to keep going. They made it to shore through a reef which left their skin with cuts and managed to raise the alarm.
Im into sailing yachts and have done Sea safety and survival training which teaches yachtsmen how to survive at sea.
Hypothermia... loosing body heat... is the main cause of death at sea. We were taught to put on warm clothing before entering the ocean.
We were taught to put on our life jacket in the water and preferably before entering the water. We were taught to save body heat by adopting the HELP position... curl into foetal position supported by life jacket. Taught the "congo line" for moving in a group, the huddle to stay together and preserve body heat. How to use the equipment...
It is really worth doing a sea survival course.
If Im flying over water I make sure I know where the exits are, where my life jacket is and study the brochure of how to put it on and how the exits work.
Then I relax.
I look out the window thinking of how long it would take to sail the miles we are doing in minutes! I check the sea conditions and think of the many days I've spent sailing between ports, check the coastline for suitable anchorages...