1. Drop to the water below through this break in the railing.
2. Return to your boat and pass through the now-open gate #5.
3. Another chopper is after you. Take the passage on the right.
4. Nab the supplies while avoiding the mines being deployed by the chopper.
5. Bank off that slope ahead to make a u-turn.
6. Steer into this tunnel to load the next area.
7. Exit the tunnel and turn left. This is a very clever sequence and the best serpentine I've ever played. Even the music is good. Push the throttle and avoid the timed explosives dropped by the chopper.
8. Steer into these pipe segments.
9. Keep an eye out for this lambda symbol, which will be on your left. Ram the wooden struts and the platform (and two supply crates) come crashing down.
10. Hang on as you grab some air, skate the top of the pipe and slide into the next segment. If you don't make it you can still steer into the next segment, albeit without the panache of a fan-boat skater-dude.
11. At the tunnel's exit you'll be greeted by two more supply crates - and another helicopter.
12. Keep right then ramp up these logs.
13. The chopper is relentless, and this choke point up ahead is particularly troublesome. If you're careful you just might be able to grab that crate ahead while avoiding the bombs.
14. More repelling CPs -- and if you look closely there are barnacles attached to the overpass ahead.
15. Keep right and speed up this ramp (inset) to fly high and land on the boardwalk in front of this building.
16. Inside you'll find supply crates plus these health and energy stations.
17. You can either return to the canal the way you came or lower your boat below with this elevator. Just be sure to land on the boat when you drop down to break your fall.
18. An incoming shell topples one of these smoke stacks. You'll be able to pass through the center of its crumpled remains.
19. Dodge the fire from the chopper and the riot truck on the overpass. Rush into the tunnel ahead to load the next area.
20. Ignore the area on the right (inset). Instead, pilot your boat over the supply crate seen here on the right. (If you get out of your boat and walk over to the crate, a head crab zombie will attack.) Climb the ladder seen on the left.
21. Follow the arrows to the washing machine at (1). Push the machine into the basket at (2). Jump into the basket and grab the health kit.
22. Jump out of the basket and pull the indicated lever. The weight from the washing machine pushes the basket down. A pulley connected to the basket elevates the ramp on the left.
23. Climb back into your boat and drive it up the now-elevated ramp to clear the barrier ahead.
24. Head left to hook up with more members of the underground. Note the supply crates on the right.
25. While you are instructed on the dangers of trekking to Eli's place, the Vortigaunt is fitting your fan boat with an infinite-ammo turret.
26. Re-mount your boat and avoid some barnacles before engaging the chopper.
27. After another ramp you'll be ambushed by CPs. Defeat them with your turret, then use the fallen fencing (just off-screen to the right) to enter the door ahead. Inside you'll find more supplies.
28. Pilot your boat through the broken fencing ahead.
29. Your turret shouldn't have any trouble ripping through this missile-launching riot truck.
30. Another ramp -- complete with supply crates.
31. Fight your way through this tunnel to load the next area.
32. Endure more of the same, then keep right at this juncture.
33. A zombie and head crabs await. A supply crate is ahead, and more supplies are up that ladder on the left.
34. Return to the previous juncture, this time keeping left. Use this bank on the right to enter the tunnel ahead.
35. Speed is not your ally here. Slow down and use your plentiful firepower to take out the barnacles and zombies in the tunnel, then these CPs as you emerge. Hold back and destroy the explosive barrels rolled your way.
36. Dodge the fire barrier by staying right, then hang back and take out the CPs and the barrels they toss before proceeding up the ramp then doing a U-turn to the left.
37. CPs spawn and you can just see a barnacle tongue ahead as well. Proceed to a tunnel on the right.
38. A little farther ahead are these supply crates in a shipping container.
39. Next up are two missile-launching riot trucks. The trick is to position yourself so that only one of them has an angle on you. Note the two supply crates on the bank ahead, and the ramp on the left -- this is your destination.
40. Exit your boat and head around to the right of this shipping container. Shoot the barrels inside (inset), knocking open the end of the container. You can now pilot your boat through the shipping container, giving you a pathway to the ramp.
41. Once again, ramp up and grab some air. Continue into the tunnel beyond and enter the canal on the other side to load the next area.
42. Search for supply crates before the chopper arrives. Clear out the explosive barrels in the area as well.
43. Your boat's turret is much more effective at close to mid-range. Hold fire until your ammo reaches 100 and then unleash your gun when the chopper gets close. Just make sure to keep moving.
44. This is a boss battle, and just as in Doom 3 there is no "Boss Bar" to show how much damage you've inflicted. You'll know you are getting close when you see the chopper spray bombs in this formation. Steer clear.
45. Keep your crosshairs on-target and the chopper will come down before too long.
46. Climb the ladder on the left and turn the wheel to open the gate.
47. Take your boat up this ramp to a firefight ahead. Matt Tharp sends word of this YouTube video showing a secret tunnel to the left.
48. Clear out the CPs (both inside and outside the building) then find shelves with supplies plus these health and energy stations inside.
49. Follow the "Observation" signs then drop down here.
50. Throw this switch to open a gate to the left.
51. Return to your boat and hit these logs at full throttle to jump through the open gate beyond. Landing on the other side loads the next level.