Cocaine is packaged in "bricks". I've seen them anywhere from 10-12 inches in width and 6-8 inches in length with a depth of 4 - 5 inches. Those are little ones, they are usually packaged in much bigger bricks. Herion is a different story and yes, mules will swallow packages of herion to smuggle through on airlines. However, a herion mule (swallower) will not likely carry "six figures" in their belly. They usually use 3 - 5 mules to get it in.
For them to carry bricks of coke or even herion in those cubicles in the jet skis - not going to hold an amount that would make it "worth it" to risk an international run.
As for the guns - I agree. It wouldn't be hard to carry one on a jet ski, albeit it would have to be smaller in size (not necessarily caliber). Definitely would be very very difficult to shoot. You would have to stop the jet ski - or slow it down to almost idle. Jet skis take both hands to control properly and even taking one hand off and trying to aim and shoot a gun would be very very hard.
Tiffany said 3 boats and the witness who watched her come in only saw one - so the other two could have stayed back and done the "clean-up". One boat getting David and the other taking care of the jet ski. Heck, even one guy could have jumped in the water and onto the jet ski and rode it off. It still had to be taken to the shore somewhere and gotten out of the water - not that easy to do if you don't have a trailer to put it on and from the looks of all this - it was a somewhat desolate place where any type of activity like that would have left trace evidence: ie drag marks, tire marks, whatever.
I'm just not going with this drug running story. It doesn't fit.