My boys (9 and 6) took surf lessons while we were in San Diego last week on Spring Break, so I have a ton of shots from those sessions. It was a lot of fun to watch.
The first day was at dusk, so although the sun was setting behind them, I had great light and fill flash helped make for some nicely exposed shots. Downside was that waters were pretty calm and my chosen shooting position resulted in images a little less dynamic than I'd like.
The second day's session was during the worst photographic conditions possible: shooting west under mid-afternoon sun with tremendous haze. I had the flash at +2 to help with fill but it couldn't keep up in burst mode ... so only 1 or 2 of a series had good light (i.e., on their faces). Still, the water was a bit rougher (made for better backdrop) and I moved around more, shooting from different vantage points, which yielded a few more interesting shots (IMO).
These were both from day 2.