Starting on yet another long straight, this circuit track is entirely based inside great caverns and tunnels. Just before going headlong into the first bend, a left-hander, you find a 4 second boost towards the right hand side and around the bend the track has a pair of columnar structures reaching top to bottom of the tunnel. Between them is a hidden 9 second boost and beyond them on the right of the track is a 4 second boost. Towards the end of the straight is another 4 second boost on the left which leads you into a sharp left hand turn. At the end of the turn you find a ramp directly in front of you (or to the left it you took it wide) which conceals a 4 second boost just past it and can be used to boost up to another 4 second boost high in front of it.
If you jump the ramp, try not to boost too much as there is a right turn quickly after it with a waterfall on it's left side. Note that this waterfall does not conceal an entrance like many others so you need to take this turn and yet it appears to offer a tunnel at it's top - those versions I've managed to get up there just dump me back on the main track again, so it's a red herring so far. That said, there is a hidden 9 second boost hanging in the air around here - it's in a different position for different versions & I have yet to find it on all versions, so happy hunting. Around the corner on the right is yet another 4 second boost but on some versions this one can be difficult to get to unless you are facing it as it appears and this is particularly dependant on the boat you have. The track continues on heading away from this 4 second boost to the left and into a short tunnel with stalactites in plentiful supply. A 4 second boost is on the left here but the track heads right shortly after it. Just before you continue around the corner you have a choice - look straight ahead and you will find a tunnel that you can jump into - and both are worthwhile. In the tunnel you will find a hidden 4 second boost and on the main track you will find a 4 second boost. On different laps get each & on the final lap go through the tunnel.
If you take the tunnel choice, turn left as you go through it. Soon afterwards you get back on the main track again as it is only a short short cut. Almost immediately afterwards you will find another choice and again both directions are of use. Both directions have 9 second boost available. Directly in front you can see a waterfall behind the wall of the track - you can boost over the wall where you will find a 9 second boost and a ramp out of the hidden section. On another lap (I'd suggest the first or last) follow the track as it heads left & collect the 9 second boost that sits in the corner ahead as the track turns back right to the place where the short cut will exit. Immediately after where the choice joins again there is another turn, this time to the left and on the inside of this corner is another 9 second boost. I recommend getting this boost on the first or second lap as just beyond it is a ramp and then the finish line.