Thule carriers are hard shell "clam-shell" style cargo carriers. These attach to Thule roof racks on vehicles and are watertight. Locks secure the clam-shell shut to prevent theft. Should you lose your keys, sadly, there is very little to do other than drill out the lock barrel, open the box, and then replace with a new lock. If you wish to open the box, and do not wish to pay for a professional locksmith, get ready to drill and put a new lock on the box.
Remove the Thule cargo box from the rack and roof of the vehicle. Set the box on a flat working surface.
Remove the plastic lock cap and expose the metal key hole and lock barrel.
Position the drill bit into the dead-center of the metal barrel. Carefully bore out the lock cylinder. Take great care to go in straight and not drill the plastic edges of the cargo box.
Disengage the lock mechanisms once you have drilled all the way to the opposite side of the barrel. Pull the lock barrel out of the cargo box. Open the box.
Install the new lock as per the Thule installation kit instructions.