Most of the people who were near death from drowning recall it as a pleasant experience. The panic and SI is a bad experience but once they let go they gulp water and fall unconscious with a feeling of euphoria. Almost all of the survivors say that it was not painful at all. What do you think is the truth??
I don't think drowning is painful, but it is psychologically extremely overwhelming.
Any method involving straight forward air supply will trigger SI. This will cause you to gasp for air, no matter how much you want to die, your body will start convulsing to make you aware you need to get air.
It is extremely traumatizing! And I don't see how you can feel euphoric while your air supply is cut.
The SN method for example imho is probably more what an euphoric death could look like.
Because that method doesn't cut air supply, but your blood cells will simply be less effective supplying oxygen to the brain, etc... Thus less oxygen is carried.
This will cause your brain to shut down progressively.
At least thats what I believe.