Mateo Island is an island near Tracy Island. It has been converted by the Tracy family for International Rescue's use in the event of emergencies and to provide additional service facilities. A monorail link to the main island allows access and transportation of supplies without drawing attention to the organization's activities.
In Attack of the Alligators!, communications are lost with Thunderbird 5. Some of the junction plates on the leads from dish number seven had become corroded. Alan was lowered onto the top of the mast by Virgil in Thunderbird 2 to carry out repairs.