jimbuckley Loc: Arizona

Horizontal camera shake.

boncrayon

There is water running down his arm that is effected by the reflection and shade of his wet suit.

hassighedgehog Loc: Corona, CA

I think it is an artifact. If you notice the front of the left leg has a white line along it.

mitxpic

And it looks to me that his back has a lighter blue halo.

artBob Loc: Near Chicago

That is what I see. Note similar on calf nearest us and similar color aberration on shadow cast by collar, back side lower neck. A light bending layer of water is possible, but doesn't explain why the hand or upper arm is not affected.

A most interesting problem, testing our knowledge of those frisky photons.

(Download)

PhotogHobbyist Loc: Bradford, PA

I would guess artifact as there is a similar line but orange along the front of his shirt and shorts.

Lucian Loc: From Wales, living in Ohio

It's artifacts. It also looks a bit like a Norman Rockwell surfing painting, if he would have done such a painting. Be happy with it, it's great.

Brokenland

Let me guess, you're using a sony camera..

davefales Loc: Virginia

Yes, it's an RX100II. Can't risk taking the Nikon out in busy surf.

davefales Loc: Virginia

Possibly, but 1/1250 seems pretty fast.

davefales Loc: Virginia

And thank you for taking the challenge.

davefales Loc: Virginia

Thanks for making me research that artifacts. I found this which may interest others:
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Blooming
Pixels on a DSLR sensor collect photons, which are converted into an electrical charge. However, the pixels can occasionally collect too many photons, which causes an overflow of electrical charge. This overflow can spill onto existing pixels, causing overexposure in areas of an image. This is known as blooming.

Most modern DSLRs have anti-blooming gates which help to drain away this excess charge.
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though I'm not sure that is the explanation for the black edge.

Brokenland

Correct and that's why I asked & knew you're using a sony camera. For years I've been telling others & they chose not to believe it or me, that sony (camera developers) write different software for their companies. Because of these differences with the digital software development, all camera companies will have some degree of errors within how the camera reads the image. Sony & Fujifilm are the main two culprits. I noticed this for the first time back in 2014 with my then new Fujifilm XP60 the images all had these black lines or the image looks as if it was layered even cookie cutterish best way to describe it.

Since then, I'll never purchase a sony or Fujifilm ever again. Chalk this image up as a learning experience or mistake. Next time.. take the best or another camera and I'm sure I'll never hear the end of my comments from others. Either you believe it or you don't. Sony & Fujifilm fails and falls short of their software development.

NOTE: As for a rebuttal from others about what I've just said above, I'll not respond to them. If the Oper has questions about what I've said I'll gladdy answer them. I'll not take part in a back and forth debate about what others have said or believe and don't try to convince me otherwise. Continue to use Sony or Fujifilm then you'll continue to see these types of errors within your shots.

davefales Loc: Virginia

Most informative. Thanks for the education.

808caver Loc: Maui

Combination of shadow and reflection of his dark clothing off his wet skin

Surfs Up !!