What sets the best surfers apart?

I was just in El Salvador and luckily (or unluckily) I was there during the lead up to the ISA games and the CT that Felipe Toledo just won. Spending time in the water with Olympic competitors and pros taught me some useful lessons.

The ability to sit deep is one of the defining factors

What allows those surfers to sit deep is 

1. Wave knowledge and positioning so they can sit at just the right spot where they can make the wave
2. Paddle fitness maneuver to position themselves, catch the wave and get in early, and deal with clean up sets 
3. Ability to make critical take-offs 
4. Mental commitment 
5. Ability to take a high-line 
6. Generate speed so they make very fast sections

This gives them the confidence to sit deeper than everyone else and therefore catch more waves. What makes it challenging is there are several very fast sections (that barrel when long period swell meet offshore winds), not to mention a very big semi-submerged rock named Mama Roca that apparently a guy hit last year with his face and had his jaw ripped off and he had to get facial reconstruction surgery to the tune of several hundred thousand dollars or something obscene!

But doing this allows them to catch more waves while respecting the priority of the line-up because these guys sit more on the inside but deeper instead of all the way out at the peak. The ticket price for entry was getting clobbered by the big set waves, but a high wave count was the reward. If you're going to do this it's extremely important not to get in anyone's way so expect to take quite a few on the head.

Sitting deep also means you'll be able to come from behind the section with speed to place your turn in the most powerful part of the wave.

When you’re in the water, I always recommend studying the best surfers carefully. Where are they sitting? Which waves are they going for and which ones are good ones and bad ones? What kind of line are they taking? How do they generate their speed? Gradually and incrementally you’ll want to push yourself to sit deeper and deeper. Don’t rush to get out there though until you’re ready otherwise you’ll get in the way and potentially get hurt.