Explorer's Cavern 1

Explorer's Cavern 1 is a cave-themed level. It was modified from Under Skull Mountain 2.

Walkthrough
There are two paths designed for two of the helmets: Knight and Maniaxe. Both can be found at the start of the level. The Knight path goes through the top half of the map, while the Maniaxe path goes through the bottom half. The flag is on the far left.

Knight Path
Grab the Knight helmet below the start of the level and climb back up. The roof of the initial structure is pathable, so climb through there as well. The goal is to stay on upper ground as often as possible, moving left. Crawl through the upper part of the structure immediately to the left. Many of the stalactite-like structures are pathable, so take advantage of this. Once you reach two columns of three mushroom blocks each, be very careful to jump up through the small hole to their left. This skips the most annoying area of the level. You'll eventually reach a short staircase. From these blocks, jump up and right to reveal some hidden steel. This makes the last part easy as well.

Maniaxe Path
Grab the Maniaxe helmet at the start of the level and move down. There's a hole in the lower left area of the structure. Jump on each of the pairs of skulls, then lightly press LEFT on the last one to fall onto a safe set of steel blocks. Take care not to fall into the lava which is bottomless. Continue moving left, navigating enemies until you reach another set of skull pairs. You'll have to move down through these, so land between the two on the right and crawl left, then right, then left, then left again. You'll crawl to the right on the last one, but be careful to land on the rock blocks below. At this point, you've reached the bottom of the map and are nearly on the far left wall, so carefully kill the Crystals and Fire Golem on your way left to reach the flag. Alternatively, move up through the pillars above the crystal, but this is harder to do. It does reward you with multiple prizes, however.

Elsewhere
As Knight, once you pass the second set of spikes and right before the up-and-down section with drill blocks, go down instead of left and crawl through a small passageway to get to a teleporter. It leads to Elsewhere 2.

Alternatively, you can instead do this with Maniaxe. Jump left from the left-most pair of skulls near the start and continue pressing JUMP to reach the same area.

Mixing Paths
The area near the Elsewhere has a Knight helmet, so you can take Maniaxe initially but still wind up in the Knight path.

The largest structure below the two columns of mushroom blocks has multiple paths through it, one of which allows you to take Knight down to the Maniaxe path. It is recommended that you reveal the Maniaxe helmet at the exit of the passageway before continuing, however.

Slightly further left, above the final set of skull pillars, there is another path that allows one to take maniaxe into the Knight path, or vice versa.

Secrets

 * If you move down through the first set of pillars in the Maniaxe route, you'll reach a small area with a Crystal, some prizes, and two ice blocks. Directly above these ice blocks is a hidden Berserker helmet. Use this helmet to charge left towards the steel structure and knock only the lowest steel block. Proceed to land on this steel block and crawl left to reach a hidden teleporter. This teleports you directly to the end of the level, which is the only way to earn the 30 second speed bonus.
 * Micromax can be found on the Knight path. At the end up-and-down section with drill blocks, jump up and slightly left from the final drill block to reveal it. The helmet makes the rest of the level fairly easy, and it can unlock a number of other secrets.
 * Four of the eight 10k blocks required to reach the 100k trip are found in this level.
 * Between the two sets of spikes on the Knight path is a small passageway with two mushroom blocks. Hitting the lower one blocks the path, but if you go back to the start and take the Maniaxe path until the Elsewhere area, you can reach this area to unlock 2 continues and a clock.
 * There is a hidden diamond in this level which requires two of the helmets to reach.

Trivia

 * The entire level was made from scratch, going from right to left, except for the far left wall, which is unchanged from Under Skull Mountain 2.
 * Fire Golems and Big Hopping skulls don't appear in any other level in stage 1.
 * Two of the Crystals are supposed to appear in the bonus area to the right of the flag, but don't due to improper placement.
 * The Cave palette has undergone far more changes than any of the other ones as of the time of this writing, slowly going from a dark brown with grey lava to a blue palette with purple-ish lava.

First Occurrences

 * This is the first time the Fire Golem, Crystal, and Big Hopping Skull appear.
 * The Maniaxe makes his first appearance here.
 * This is the first cave-themed level.