I'm sure many of you were told as children to wait at least an hour after eating before swimming. This however has been proved to not be true. I found on snopes.com that you can actually eat as much food as you want and go swimming immediately after, without drowning.
Although you may get cramps, this is not from eating and will not cause you to drown. There are a certain type of cramps called "oxygen deprivation stomach cramps", which is caused by lack of blood to your diaphragm due to pressure form the lungs and abdomen. However, there is no real link to this, eating and drowning. This is an example of correlation vs. causation. Correlation isn't causation, variable A does not necessarily cause variable B, meaning that eating before swimming does not cause a person to get cramps and drown. Although they may be correlated in someway, you may develop cramps while swimming after having eaten, but this does not mean that you are going to drown. There have been no recorded deaths of drowning from eating too much before swimming. It is vey likely that this myth was made up from some over protective parent that was paranoid about their child drowning and it somehow became very well known.