Thin Floors are a type of platform that Kirby and other playable characters can pass through either upward or downward. They can take on a variety of looks, but are distinguishable by their particularly thin appearance, especially in comparison to surrounding 'hard' floors and ceilings.
From above, a character can pass through a thin floor they are standing on by crouching. In newer titles, this can also be done from the air by initiating a fast-fall. Despite characters' ability to do this, most airborne attacks cannot be used to pass through a thin floor, and most projectiles will not pass downward through them either.
From below, however, thin floors are not a hindrance in any way, and can be passed through as if they are not present. This includes projectiles that would normally be stopped by ceilings such as bombs and arrows. The only exception to this is Kirby 64: The Crystal Shards, where Kirby performs a 'get-up' animation when he passes upward through a thin floor.
The Super Smash Bros. series also makes use of thin floors.
- There are a few instances of platforms that can be passed through from below, but not from above. These are often referred to as 'semi-soft platforms' or 'one-way platforms'. They are typically distinct from standard thin floors in appearance.
- Notoriously, in early games featuring the UFO ability, Kirby was unable to pass downward through thin floors while he had it.
- "You can move ↓ to fall through the thin floors in all the stages!" —Loading screen tip (Kirby Fighters 2)