The HQ is the command center of the Octopod. Inside, the octonauts can control things like the octo-alert and the moving of the Octopod. The computers inside are normally controlled by Dashi but sometimes controlled by others.
Inside
Inside the HQ there is the octo-alert, which is used in all the shows. Then there are computers and the hot chocolate maker. One of the computers can be used to see other crew's personal pictures, which sometimes appears in the series.