Hi and welcome to Wetpixel!
You should definitely NOT be shooting TIFF - There are many disadvantages and few advantages. I suggest that you shoot JPEG for your first dive or two, to get the hang of the camera, then shoot RAW on your next dives.
Basically, a TIFF is a RAW file that has been "pre-processed" by the camera and "fixed" with those colors. When you shoot RAW, you can adjust the color on your computer, then save the file as a TIFF. It gives you a LOT more control.
Not to mention, it takes AGES for the camera to write a TIFF file to your flash card.
Cheers
James Wiseman