I often use a wide angle lens when I'm diving. It's just a way to get a larger field of view. This is useful for me, because shots taken while diving tend to be, of necessity, taken from close to the subject. Moving back from a subject under water to get a larger field will REALLY screw up your lighting.
Panoramics are a series of pictures taken from while rotating the camera around a common pivot point, and then splicing the pictures together.
There are also panoramic lenses which, as I understand them, take a 360 degree photo on one snap. I've never tried one, but the samples I've seen seemed to have a lot of distortion in the image, sort of like a funhouse mirror.
This is a shot I took off Cozumel of a scorpion fish (they're quite venomous, and their camo is one reason why good divers are anal about bouyancy control and never ever touching anything...). Without the wide angle lens, I'd have had a choice of moving back or not getting the whole fish in the frame. Moving back, thanks to the refraction of water, would have resulted in the loss of much of the color (although this one is laying in a bed of seagrass, so there's less color than in other places). Even big strobes are only useful at short range underwater.
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Another scorpion fish, laying under a reef, showing the color of the coral.
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This is an unfiltered shot of a reef, taken from too far away for strobes to be of any use. Not too exciting...
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This is the same section of reef, from much closer, showing the color these reefs really have. It was taken directly below the round coral in the center of the prior picture. The cowfish in the picture is about 2" long, to give you an idea of the scale.
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This is a panoramic shot of Amberley Castle in southern England. Sue and I got married on the battlements right next to that gatetower on the right (as you look at the picture). It's spliced together from two other shots.
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These are the two pictures I used to create the panoramic shot. Obviously, moving back to capture the entire front wall of the castle would have resulted in very little detail, even if I later cropped and zoomed the shot.
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If you look at the panoramic shot carefully, you will be able to see where it was spliced. In my defense, the shots were taken without a tripod. For best results, use a tripod to ensure that all the pictures are taken from exactly the same point of view.