Puftoss is the boss of the area Gloomy Galleon in the game Donkey Kong 64. Puftoss is a giant Puftup, a type of blowfish. He is faced by Lanky Kong who is in a coconut motorboat. Puftoss cannot be hurt directly by Lanky: instead, Lanky must use his motorboat to drive through several DK Logos which appear throughout Puftoss's arena. If enough of the DK Logos are driven through, large poles will rise out of the water and electrocute the boss.
To stop Lanky from raising the aforementioned electric poles, Puftoss has several attacks: he can shoot fireballs, create shockwaves and send smaller Puftups after Lanky. The shockwave is an instant one-hit-kill if it hits Lanky, but it's only done in the second and third phases of the battle. After Puftoss is electrocuted enough times, he will deflate like a balloon, flying into the air, falling back to the water and going back underwater again (perhaps to heal his wounds). It is not revealed what happened to Puftoss, as it was with some other bosses in the game.
On a side note, as Puftoss takes damage, the DK Logos get smaller and Lanky has less time to get all the large poles to rise out of the water.