The Underwater Tunnel is a tunnel found on Harmony Island under the Saradomin statue, accessed during the quest Great Brain Robbery. It's connected to the church on the island, which is barricaded by Mi-Gor's zombie crew during the quest. A fishbowl helmet and diving apparatus are required to enter. Ten level 49 zombie pirates can be found within. This is one of the few areas where the brine sabre's special attack, Liquefy, can be used, as it only works underwater.