Cheat Menu Cheats for Donkey Kong 3:
Enter these into the 'Enter Cheat' screen found in the 'Options' menu.

kredits - View Credits
music - Music Player (Sound Test)
harder - No Midpoint Barrels
aqua - Get all 98 Bonus Coins
Tuffer - Removes DK and Star-Barrels (only on new game)
Extras - Allows you to play Funky's, Cranky's and Swanky's Mini-Games from Main Menu.
Monkey - Start game with 50 more Lives

Donkey Kong Country 3 Secrets:
Reach Krematoa - To reach Krematoa (the Lost World), go to the four rocks east (left) of Mekanos. Stay on the rocks as you circle around it clockwise about four times and the volcano will replace the rocks.

Reach Pacifica - To reach the new exclusive to this game Oceanic based world, when you get the jetski use your turbo up the waterfall right where you started the game. Go up the waterfall after that and swim to the very hidden world marked by a K Rool Flag

Best ending - To obtain the best ending in the game, you must collect every Bonus Coin in the game, every DK Coin, and every Banana Bird, and defeat the last boss in Krematoa.