Roll over on your back and release your weight-belt, but hold on to it until you get it properly stowed. If your kayak has a tank bay in the rear, you'll probably find that it's easiest to pull the tank aboard by the boot or bottom of the tank. Keep your finned feet in the water to provide stability while you are bringing the tank onboard. It may be a little different on the Scuppers and Prism where you might bring the tank into the cockpit area first. You'll probably have to remove the regulator and BC before you can get it in through the front or rear hatch.
Newcomers often seem to flip over on their kayaks for no obvious reason.
Sometimes a wave or swell sets them off balance, or, they just forget where up is. It's no problem if everything is secured properly. And Using Your Dive Kayak. Everything discussed in this article and more is covered in over 220 pages and nearly as many graphics, photos and drawings in an 8.5 by 11 inch, photocopied, spiral bound format. We know of no other published book of instruction.