Recommendation: ****
Effort required: some. presumably you will require a weight heavy enough to sink you, or some other preparation, if you don't naturally sink.
Messiness: variable but probably pretty bad. if it takes more than a couple of days to find your body, things will get ugly.
Pain factor: what, are you crazy? unless you can achieve a high degree of Zen detachment this will really suck.
Drama: if you can manage to relax and drift off to sleep as your lungs fill with water, it could be quite beautiful and peaceful under water.
Certainty of death: quite high. if you sink yourself via weights you won't survive. it's also really hard to find drowning victims if you are attempting to save them.
Wimp option: not too bad if you bring a knife to cut the rope tied to your leg. just make sure you have enough strength to swim back.
Other points: If you aren't found quickly, this will provide an incredibly disgusting surprise for some poor sap. Imagine leeches, crayfish, etc. In addition, you could skip the whole water part, and just tie a plastic bag around your head. Drama is reduced a bit as the bag will fog up a lot and look kind of silly. Remember to brush your teeth if you decide on this method. Actually the plastic bag is a recommended (by Kevorkian) addition to most non-violent suicide methods.
