I personally want to jump from a bridge into the sea to CTB. I myself enjoy the sea and would like my body to hopefully disappear and that is enough for me to probably ignore the potential pain. Though if I were you I would go for a painless method if you are concerned with pain. You have the potential to break multiple bones, throw up seawater, may not be able to swim if it fails, the waves will thrash you body against the rocks. Yeah, throwing yourself has a very big potential for pain. You might not even die, what if you get saved by police, a coast guard, or a "good Samaritan" and maybe disfigured or paralyzed. A woman even shot herself when she threw herself off the Golden gate bridge to avoid the pain on the other hand a guy jumped in for "fun" and came out with a torn lung and other injuries. So yea, probably the most painful and possibly unreliable method.