You start this one in a very wide section of track. Stay roughly to the left, even though the first turn you'll make is to the right. As the left-side rock face starts to encroach, prepare to make a sharp right to head for a ramp. Head straight up the ramp and collect the 9 second boost. As you leave the ramp, turn your boat to the right and start boosting as soon as you collect the boost. After flying over the archway where the 9 second boost is, head down the straightaway that will now be apparent. Don't boost all the way down this straight as there's a sharp left turn at the end.
Around the left is a boat - stay to the right of it and head for the 4 second boost in front. You will hit the next checkpoint as you go around the right-hand turn. At this point, a ramp is in front with a four second boost. In the air from that four-seconder, turn to your right and boost down the next turn. This flight is a repeat of the one at the start. Don't boost too far as the next turn is an even sharper left with a boat on the right-hand side which can easily be in the way if you're not used to it. Past the boat and under a huge archway is another 4 second boost and another checkpoint on a right-hand turn.
Immediately after the checkpoint is a left-hand turn and a waterfall drop. Try to be on the right of the drop to land on a 4 second boost and then make a right-hand turn into a tunnel. Inside the tunnel after another right hand turn, a part of a cavern looms out. Stick to the inside as there is a rock in the middle of the track. To the left is a 4 second boost and to the right is a 9 second boost, so stick to the right (it is possible to get both boosts if you go to the left, but the gain is not worth it). After the short split in the track, the tunnel is back with a left-hand turn and a short straightaway ending in another sharp turn, this time to the left. A 4 second boost will be hanging in the air near the end of this next short stretch followed very quickly by a left-hand turn, so try to jump early and be on your way down when getting this boost.
After getting the hanging boost, go left but take it wide. You'll be approaching a checkpoint with two boosters - one 4 second in the middle and boost through the 4 second boost at the 9 second boost. Immediately after the 9 second boost is a small drop and a cavern where the main track goes to the right with a waterfall in front. Head under the waterfall's middle and shortly after you'll find a 4 second boost followed by a left-hand turn and another straight tunnel. A sharp right-hand turn ends the straight part and after an archway a 4 second boost precedes a left-hand turn. Take the turn wide until you're used to it, as you'll need to get used to straightening up for the ramp that's at the end with a 9 second boost. It's easy to miss if you're not in good control of your boat.
On landing, if you have good control of the boat and are going fairly straight, you'll land on a 4 second boost immediately followed by a left-hand turn and a checkpoint. Head down the course after the checkpoint and turn sharply to the right. Go straight through the big cavern that now surrounds you, and at the ramp pick up a 9 second boost. As an alternative to this jump to two boosts, look to the left to see a quay and a cave tunnel hidden away just towards the end. Take the cave for a 4 second boost and exit at the next checkpoint. If you head for the ramp straight on you will be able to hit the helicopter (no bonus for it alas!) and land on another 4 second boost. This is immediately followed by a left with another hanging 4 second boost. If you have plenty of boost, don't bother with this one as there's a sharp right immediately after it to get you to the next checkpoint and join where the tunnel exits. If you need to get it, jump early so you're landing as you get the boost.
Past the checkpoint and the right-hand turn you'll find a bridge with two large archways with a 4 second boost in each one. Depending on the version you're playing, you may also be able to see a bridge in the distance with a 9 second boost. Ignore the 4 seconders - it's the 9 second boost you're after. To achieve this, head straight at the middle of the bridge where you'll see a ramp. Boost up the ramp and you'll get an extra jump and fly over towards the 9 second boost. As you fly, try and aim at one of the 4 second boosts below you. If you can't, don't worry as you should be able to get to the finish on the 9 seconder you've just caught. Immediately after the 4 second boosts is a left-hand turn towards the finish. The ramp doesn't really matter as you should have enough boost left to bounce your way to the finish.