All death is tragic, but sure, everybody knows that some types of death are worse and more painful than others. If given the choice, I think that most people would choose a quick death over a slow one, and we all want death to be as painless as possible. The diving story is very tragic though.
Yes, in certain situations, it is better to die quickly than to endure a longer death with greater suffering. If you know that there is no hope of surviving the situation, and there is an option available to shorten your suffering, take it. For example, if you are trapped in a fire with no way out, but you have a gun or knife, it is better to shoot yourself or bleed out rather than burn to death.
it is certainly better than going through all the suffering he would go by letting himself drown to death. When the life comes to an end, it is up to the dying person to choose his fate. I find that the only fair thing to do. So, yes, stabbing himself to death is much better than some other scenario.
Death is something that every person will experience at least once, if not several times throughout their lifetime. The question is then asked, is there any type of death that is better than others? This however has a wide range of grey area due to the fact that everyone experiences life differently and each person has different fears of death. One person may view drowning as one of their biggest fears and views this death as the worst possible case scenario. While another may view burning alive as the least desirable death to experience. Simply put, there is no definite answer to what death is "better" for this is something that is decided by each individual person rather than as a set standard.