Wario Land II DX: Part 38: Chapter 2 - Story 4 (Secret Exit)
3After beating the second extra Chapter 2, it will just link back into the regular Chapter 3: Maze Woods.
Instead, I'm going through Story 4 of the regular Chapter 2, SS Tea Cup, where Wario has to "Drop the anchor!!" of Captain Syrup SS Tea Cup pirate ship!
At around 2:28, past the cracked wall to the left, there is another more seemingly-ordinary wall that Wario can't break through.
This wall is secretly hidden Enemy Blocks. So pick up a nearby enemy and check them towards that wall to finally break it. This will lead you through the level's secret path.
At the end of this path, instead dropping the anchor to hold the ship down, you instead have Wario break open a big blue clog!
This will cause a massive leak in the SS Tea Cup, causing it to sink into the deep sea, instead!