Thanks to all for your great suggestions. I learned a lot!
Summary of what I learned:
- Keep the shutter speed fast (safe to say 1/1000 or faster) for action sports like surfing.
- Use 100 ISO if possible. (It was and I didn't)
- Be careful about over-cropping so as not to hide the context of the surfer.
- Keep aperture down a bit for better color. (Hadn't heard that one before.)
By the way, surfers were about 50 meters max away from me as waves broke off a point of land. I was on the point about 15 meters high. But I did crop some and perhaps should have left it wider. A 500mm lens, in this situation, would have been a study in nostril hairs, though.
Another constraining factor was that the sea and sky were both a definite gray color. When I bumped up color saturation it really only affect the colors on the surfboard. Any thoughts/tricks on shooting in a very gray environment?
I very much appreciate the opportunity to learn from those who commented. Thanks all!