Keel Mango sprite from Paper Mario: The Thousand-Year Door
Strangely enough, the Keel Mango is not available when Mario first arrives at Keelhaul Key. In fact, it does not become available until Mario has completed the chapter and returned to Rogueport. This is possibly to ensure that Mario must give the coconut to Flavio in exchange for the Chuckola Cola, as giving him any other food item results in him asking for something more tropical. Since Keel Mangos are also tropical, this must be why they are made unavailable at this point in the game. Once the Warp Zone has been activated, it is a very simple matter to get Keel Mangos by hitting a short green tree just at the left of the pipe.