Surfing Waves

Hello,
I'm a translator and I'm currently working on a surf documentary. However, I'm not an expert in this sport so I would appreciate your help with specific vocabulary. For instance, in this passage:

"You could take off and it gets exciting and all of a sudden you come round the corner and you hit the [UNSURE OF WORD] and it could be either barrelling or it could be dumping at you and then the hold downs of that place is crazy."

There are a few words missing, I hope you can understand the general meaning though.

Correct me if I'm wrong: a barrel is what they also call a "tube", and a dumping wave is that wave that breaks all of a sudden, almost shooting you away or deep into the sea. Why this emphasis between barreling and dumping? The whole point is that you can fall and get caught by the undercurrent, isn't it?

I'm confused.

Thanks a lot.

If you look at the drop down menu form above this page there is a Surf Terms page with both of those terms in it. Barreling is tubing and dumping is just throwing over in a huge section like a closeout. Hold down means how long the wave holds you under water so apparently that break has a lot of water in either situation (barreling or dumping) and the wave pushes you under water and holds you there for a long time.

Calvin wrote:Why this emphasis between barreling and dumping?

Barreling, good. Dumping, bad.

Yeah barreling is a nice wave and dumping is not a good wave so either way this wave pushes a lot of water shoreward and can hold you under water for a long time. The undercurrent is not a factor in this statement. Hold downs are associated with the wave breaking and the force of the wave itself and not the currents around the area.

All good help so far
DO NOT under any circumstance use the word "gnarly" in any part of, or in any way in the documentary.
Any credibility it had would instantly vanish

Kowabunga!