Fisheye lens options and advice
Tokina has a 10-17 fisheye. It's pretty good. I mainly use it underwater.
These shots of humpback whales were taken at 10 mm. Objects are much closer than they appear
Whaleshark shots at 10 mm
Topside shot at 10 mm
Another topside shot at 10 mm. It has good color rendition and is fairly sharp.