The boss fight against Koala Kong (コアラコングは ちからもち lit. Koala Kong is a Strong Man in Japanese) is the second boss level situated on Wumpa Island in a volcanic mine, which is the only type of level in the game and Koala Kong is the third boss of Crash Bandicoot. It is the seventeenth level of the game (including boss fights) and the final level of the second island. It starts with him showing Crash his muscles and then he jumps to the left and starts throwing three rocks at Crash. He's across a lava river and behind a mine cart track but it is still operational as mine carts pass, blocking Koala. Koala has four hit points rather than the past bosses, Papu Papu and Ripper Roo, who had three. When Koala picks up a fourth rock he'll walk very slowly and throw it at Crash. It stops in front of him and if he spins it back, it'll hit Koala and take one of his hit points away. TNT crates start dropping from above Crash as Koala's health goes down. There will be more mine carts passing. When Crash spins the final rock at Koala, he'll fall on his back and Crash can move on to Cortex Island. After Koala is defeated, no more mine carts will go past. A good thing to keep in mind is in this boss fight, TNT crates only fall in the middle of the area Crash can stand on.
This corresponds to a save file at this level (42%, 0 keys, 5 gems).