The second level is arranged in the shape of the Japanese kanji for mountain: 山. One crystal can be found by exploring each of the three northern tips of the map. There are three boss spiders in this level, and only one guards the path to a crystal diamond. Another guards the one and only enhancement item in the entire level.
If you find yourself falling into a gap or a hole, you will arrive in the bottom room of the underground which spans two rooms vertically. From where you land, you can see and collect Astro Pants. If you continue up from there, you will reach a dead end with a Cosmo Ball. Shoot out the spikes to access the left path, and follow it around and up to the stairs that will return you to the main map.
You begin at the very bottom of the central path. From the start, head north. As you advance, you will have to fight your way through some Imochuu worms before the ground will literally tear itself apart. Long gaps will appear in the ground which you must walk around, or jump over. More Imochuu wait for you above until you reach a fork in the path. The left path is guarded by blue crows, but it has some items. The ground at the end of the right path will rip open, and unless you've collected 2 or more Power Shoes, it's not worth trying to jump over, so take the left path.
A Hotchkiss cannon will appear once you're on the other side. Then another boulder will split the path with blue crows on the left and wolfmen on the right. Some more Imochuu and Beebees will guard the path until you get close enough to the stairwell entrance to the cave. Two land mines are set up near the entrance and can only be detonated by walking close to them. When they explode, head inside.
Inside the cave, you can attack the wolfman right away, but you'll have to wait for the dinosaurus to raise it's head out of the ground before you can kill it. Collect the Power Shoes and head left. You'll face the first Bemu Spider boss. If it hits you with the webs it spins, it will dash over to attack you before you can free yourself. You can remain fairly safe by shooting from the entrance that you arrive from. Even after you kill the spider, the spikes at the bottom won't disappear until you detonate all four land mines. Head to the room below, shoot the Crystal Diamond Guard dome, and collect the crystal.
The path to the west crystal
While you could go back to the cave entrance at the top of the center path, travel all the way down to the bottom, and walk left until you reach the west path, there is a bit of a shortcut that will save you some time, and help you collect a valuable item on the way. Return to the first room where you arrived in the cave, and take the right exit. Walk along the path, fighting the two blue crows and one of the wolfmen when you reach him. Shoot out the spikes that guard a Cosmo Ball and Astro Wear, and head down the right path. You will encounter the second Bemu Spider. Defeat it and collect the Fire Rate Up enhancement that it guards.
Then work your way back to the room above, and shoot out the spikes that block you from accessing the left path. Destroy the wolfman and continue down to the room below, and follow the path to the room on the right. If you'd like to collect Astro Pants, fight the two Imochuu worms on the left path and follow it up to the dead end above. Back in the lower room, clear out the enemies and the spikes and collect the Power Shoes. Then follow the right path up to the room above. Cautiously clear out the enemies and take the stairs. You will now find yourself at the end of the left dead-end side of west pathway. Head all the way down, and beware of the gaps that are created in the ground just before you reach the clearing.
Whether you retraced your steps and came all the way down the center path, or if you navigated your way through the cavern, you should be down at the bottom of the west path. All that you must do is head up the right side. As you leave the clearing, beware of the ground that splits open, and the volcanic rock that flies out of the center mountain spine. There are only a few enemies to clear before you reach the staircase entrance to the cave above. Head inside.
Some Blue Crows, a Dinosaurer, and two land mines are your only enemies in here. Once they are clear, begin shooting at every block in the room. Three are hiding items for you to collect, while a fourth is covering a staircase to a room below. Once you find the staircase, head inside and you will find the second Crystal Diamond Guard dome. Destroy it and collect the second crystal.
From the second Crystal, return to the West path, walk all the way back down, and return to the bottom of the center path. Then continue walking east and you will encounter the third Bemu Spider. Defeat it, and collect the flashing apple that it leaves behind. Then continue on to the east so that you reach the bottom of the East path.
Defeat the Kinoko mushrooms that bounce around here, and destroy all the blocks so that you can find some easy items to collect. As you advance north a little bit, you will find the feature for which this stage is named after, the Stonehenge. Blue Crows lie in wait for you to approach the monument, and a large Eagle will also fly down to lead the attack against you. Clear out all of the birds. The two blocks inside the Stonehenge contain Cosmo Balls.
As you continue north and walk through the forest path above, volcanic rock will begin to fly out of the right side of the forest. When you see a wolfman and a dinosaurus, be careful as one more tear will appear in the ground before you reach the staircase entrance. Taking these stairs will drop you in the small contained area of the dungeon that was inaccessible to you if you previously explored this region. Walk north to reach the second stairwell above, and take the stairs to be lead to the third and final Crystal Diamond Guard dome. Destroy it, collect the crystal, and hop in the transport to be taken to the next stage.