Warp Barrels are rare, but extremely helpful barrels that are found in the Donkey Kong Country Series. Warp Barrels take the Kongs from the beginning of a level, to near the end of it, but it must be found first. This proves to be very difficult because warp barrels are invisible until you a Kong jumps into one. They are also usually put in dangerous or hidden locations. If the player does know where they are though, they can get through tough levels with ease, or get through a speed run much faster.
Donkey Kong Country
Warp Barrels first appeared in Donkey Kong Country, and were found in some of the earlier levels, such as Ropey Rampage. They are not very common though, only appearing in a few of the early levels. They are well-hidden, and usually put in dangerous places. In the Game Boy Advance remake, more Warp Barrels were put in the levels then there were before, and the barrels even got their own theme room, with bananas spelling out the word "WARP".
Donkey Kong Country 2: Diddy's Kong Quest
Warp Barrels appear again in the sequel, Donkey Kong Country 2: Diddy Kong's Quest. They are the same in most aspects, but instead of being placed in random early levels, they were put in ever single level of the first two worlds (Gangplank Galleon and Crocodile Cauldron). Warp Barrels are still very hard to find like they were in the last game, and are still placed in dangerous areas. When jumped into, you ae taken to a secret room much like the one in the Game Boy Advance version of the first game. The bananas make a "!" instead of spelling out a word, though.
Donkey Kong Country 3: Dixie Kong's Double Trouble!
Warp Barrels make another appearance in Donkey Kong Country 3: Dixie Kong's Double Trouble!. They are the same as in the last game, being in every level in the first two worlds (Lake Orangatanga and Kremwood Forest). When warped, the Kong(s) would be warped all the way to the end flag.