Clash at Demonhead/Route 37

Description
Assuming you arrive from the left exit, you will be immediately greeted by a set of enemies. The two high enemies fly over and drop when they are above you. The lower enemies are the type that fly across the screen in a wave. A little further in, and you'll see a large bouncing enemy. Remove it and proceed to the waterfall.

Be careful at the waterfall. If you drop to the bottom, all you'll find for your troubles is a gold bar set, and a very long climb back to the top. Avoid that and only climb up to the screen above. Watch out for the enemy flying across the screen, and climb up as high as you can go before pushing off to the left in order to land on the small ledge below. Then jump up and continue climbing up the left side of the screen to the next section above.

Do your best to avoid the heat seeking missiles coming your way as you reach the top. Continue to the right, where you'll encounter a few more heat seeking missiles. When you reach the water, several slowly falling enemies will be floating above it. Clear them away, and then equip an Aqualung and jump into the water.

Push down and swim below and follow the underwater path as it leads down two screen, over to the right, and back up to screens. Evade or destroy the various creatures that you encounter as you swim through the water. Once you reach the surface, hop out of the water and exit through the right.