Duke Torvuellé hands you a datapad with the necessary information on it.
"The Gungans are ruled by a quasi-religious caste known as the Bosses," the Duke says. "For the most part, the Bosses were swayed to our side by your Jedi friends that were here during the Battle. They committed their men and resources to the fight, for which we will be forever grateful.
"Once the battle was over, one Boss retracted his support and retreated to his underwater city with his people. He has permitted no-one to come to his city or discuss things with him.
"I think you can see our problem."