Kayaker and Red Bull athlete Rafa Ortiz is no stranger to large drops over waterfalls. Rafa's film, Chasing Niagara, follows his journey to take on what he says is the world's scariest waterfall. If that's not enough adrenaline for you we also mined Rafa's brain for his picks of the world's scariest waterfalls to kayak. Take it away Rafa...
More: Watch Chasing Niagara on Red Bull TV
1. Niagara Falls, USA/Canada
I stood in front of Niagara Falls a long time ago and realised that it was runable in a kayak. The whole project was born with that crazy idea and crazy motivation. You can't close your eyes and scream like a little girl on the way down. You need to keep control. You're controlling your angles all the time, you need to be reactive the whole way down. You need to be performing every split second.
Niagara is like the next level scary, it's off the scale.
Niagara has it all, it's like putting all five of the waterfalls below together in one. What makes it a lot scarier, and a little bit harder, is that transition from flat to vertical. It's pretty steep - a 90 degree angle - you need a good angle on the way down to plunge vertically into the pool below.
2. Angel Wings, Mexico
Its really big, there's about 90ft of free fall. It's got a peculiar entrance to the waterfall because it has two runs that sprays water, which is why we call it Angel Wings because it's got a sort of wing feature at the rim. It's also got another 100ft tall waterfall right in front of it so whatever happens you need to be able to get out before you head to the next waterfall!
3. Tomata II, Mexico
This is a crazy one. It is one of the most technical waterfalls on the planet. It has a big rapid coming into it with three moves that are really tricky separately. Putting them together back to back makes it really complicated. The rapids lead right into the waterfall which is about 80ft high. The water by itself is scary but the scariest part is getting to the right place at the edge of the waterfall.
4. Big Banana Falls, Mexico
The crazy thing about it is that it comes out of this tight canyon so the only way to scout the waterfall first is to rappel it. You're hanging off a rope attached to a tree like a piñata trying to look at your line as you're dangling off a cliff. Then to actually run the waterfall you need to rappel with your kayak from another tree that's upstream. The only way to get out of that canyon is to get in the water and go over a 128ft waterfall. It's also not a perfectly straight approach so you've got to be moving a bit left and right, trying to hold your angle and making sure that you are bow down so that you can plunge the waterfall vertically.
Watch Rafa Ortiz drop 40m over a waterfall
5. Palouse Falls, USA
It's the biggest one of all at 189ft tall. It's about the friendliest of these falls in that it has a pretty good, flat pool up top and then it has a pretty big one at the bottom. The scary bit is the height. You've got to come in at the right speed and position, before setting a straight angle so that it's a good line.
6. Sahalie Falls, USA
It's about 80ft high but it's risky as it's got a really tricky approach. It's a very technical move to get to the right place at the lip. You've got to make sure that you're in the right place at the right speed. The trickiest thing about it is after 80ft of free fall there are pretty big rapids right below. Whatever happens you've got to be able to get out before coming into the rapids - if you go under a log it could be deadly.