It's not so much that I am wrong, as that a) the plural of anecdote is not data, and b) your experience is not blinded, and therefore may be biased.
The statement that significantly low potassium is rare in healthy, unmedicated adults is a true one. In addition, despite what has been written, dehydration is also rare in people who are not dealing with high temperatures and who have unlimited access to fluids. Caffeine-containing fluids are net hydration, as are sugar and electrolyte solutions, so long as the electrolytes are not hypertonic. There is a LOT of mumbo-jumbo in the health foot literature, but little of it has any basis in science.
Low magnesium is common in alcoholics, but not very common, again, in healthy individuals eating a varied diet.
The bottom line is that diving, and kicking with fins, uses muscles we don't always use, in ways we don't usually use them, and the muscles are likely to cramp. Conditioning, stretching, and sometimes reducing the workload are all strategies for avoiding cramps. If you want to eat bananas or drink orange juice, have at it -- it's not going to hurt anything except your waistline!
