Yet, the preferred way is to write Scuba. English evolves, and while I know what swag stands for, it's become a word in the English language. There are a lot of evolutionary words out there: GP evolved into Jeep (that's how everyone pronounced it), and with the advent of twitter/texting, we even see words such as idk, etc.[OCD]
SWAG is an acronym (Scientific Wild A$$ Guess) and should be capitalized, just like SCUBA. Just sayin'.
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In that regard, instruction also evolves. Kneeling, once accepted as normal is anathema to quite a few of us. Some of the Scuba instructional practices of yesteryear were just as dangerous as putting 30 pounds on a 120 pound kid.