From Donkey Kong Wiki
A Bonus Level is a secret area found in nearly every single level in the Donkey Kong Country series and later games as well. Bonus levels are mini-games that yield rewards when done successfully.
 Donkey Kong Country
Collect the Bananas!
- Speedy Swing Sortie: Climb the trees and swing from vine to vine to collect all the coins.
- Mad Maze Maul: Defeat all of the enemies in the maze, then head for the finish line.
- Splish Splash Salvage: Swim down and collect all the coins in the barrel.
- Minecart Mayhem: Avoid the TNT carts on the track by switching lanes when they come close to you.
- Stealthy Snoop: Sneak through the maze without getting caught to the finish line.
- Teetering Turtle Trouble: Turtles are spinning around on the snakes' tails. To keep them spinning, shoot melons at the snakes' mouths. If a turtle falls, the game is over.
- Big Bug Bash: Use a fly swatter to swat the required number of flies within the time limit.
- Kremling Kosh: Shoot the Kremlings that pop out of the barrels. Regular Kremlings are worth one point, and red ones are worth two points. Shoot the required number before time runs out to win the game.
- Peril Path Panic: Shoot melons at the Klaptraps to subdue them so that the Banana Fairies can safely cross to the other side.
- Beaver Bother: The player controls a Klaptrap and tries to chase the Gnawtys into the hole in the center of the barrel. The player must be careful not to fall into the hole themselves, or they will automatically lose the game.
- Batty Barrel Bandit: Stop the four reels of the slot machine on four bananas to earn a point. Earn the required number of points to win the game.
- Stash Snatch: Collect all the coins in the maze, then head for the finish line.
- Searchlight Seek: Using a spotlight, the player has to find and shoot the Klaptraps.
- Busy Barrel Barrage: Use your shooter to blast the Kremlings. If you let one reach you, you lose.
- Krazy Kong Klamour: The lights will repeatedly turn on & off. When they turn on, shoot the Golden Banana. Avoid hitting any of the Kongs, because if you do, you'll lose one point.