The entrance to Zooknock's Tunnel is in the jungle south of the Ape Atoll. Climb down the ladder near the red exclamation mark to enter it. There are many traps in this dungeon; rockslides and traps that can hit up to 9 damage. Also watch out for the zombie monkeys, which can poison you, and the powerful skeletons, and tiny level 1 poisonous spiders; all are aggressive. Because of all the traps, this dungeon is considered a very bad place to train; it's primary use is in the Monkey Madness quest, to reach the 10th Squad's mage, Zooknock. For more information on this, read the Monkey Madness quest guide.