Springboards appear only in the Ice Caves.
They are randomly placed on the ground and can be seen as a raised bump. Stepping on a springboard will launch you into the air, roughly 5 to 6 tiles high and to the side if not placed in the center. They are extremely efficient at catching you of guard.
Normally, this wouldn't matter too much, but in Area 3 it does for several reasons. The first being: All of the levels in Area 3 are bottomless, meaning you will instantly die if you fall into the pit. Secondly, springboards tend to be generated on ledges, and unexpectedly being launched into the air is likely to cause Fall Damage unless you have a Parachute, Cape, or Jetpack to slow your descent. Thirdly, the bounce could lead you falling in front of a monster or landing on spikes.
However, falling onto a springboard from a great height will negate any fall damage you would have received otherwise. A spring will also make you jump further, potentially allowing you to access parts of the level.
Yeti can also be launched by springboards, which can be both unexpected and deadly. They are triggered by almost anything on them, including you, yetis and stones. They however, can not launch big enemies, like the Yeti King.
Springs can be destroyed by breaking the block underneath them. It is also possible to step on the very edge of the block the spring is on, and not get bounced.