World 3 introduces a two new enemy types - a passive flyer, and one that can jump over obstacles. It will also have hidden switches in the primary path, but is otherwise an easy stage. If you want to start a game on this stage, use the password "WIZARD".
When you reach the first cave blocked by the boulder, there is a hidden switch just above the ledge. This switch destroys the boulder, granting access to the coins in the cave. Note that jumping down is a one-way trip unless you picked up a create earlier in the world.
The cave below the exit contains six bombs, and its switch is found just above the cave entrance. If you are retrieving these bombs, you may want to place a crate in fronr of the entrance. Alternatively, you can use these bombs to destroy the enemies that approach, or instead run past them (and taking a bit of damage.)
You can exit this world, or attempt the secret. To the right of the exit is a switch that reveals platforms, located just past the ledge and requires a high jump. This switch reveals platforms that you can use to cross the water, and a blocked cave. The switch to open this cave is on the first step upward, and the yellow key for this exit can be reached in the cave.
This world is more of a treasure area, where you can collect coins and other items, but enemies are still a threat.
Down the ladder and to the left are 13 coins.
To the right and up the ladder and to the left are 16 coins and 9 bombs. There is a chest that is to the right of the ladder. Cross the collapsing bridge only when you can get the coins in a single run. Bring a crate with you before going past the arrows.
The next ladder leads to coins, and a set of items that can be reached by the little player.
There is a shop where you can purchase a balloon. If you want to use it, continue right past the coins and into the large area, stopping at the second torch. Inflate the balloon here and jump on it. This allows you to collect 16 coins in addition to an item chest.
The exit is at the bottom-right corner, and there are no significant obstacles beyong the spiders hanging from the ceiling.