Settings > General > Passcode Lock.
Turn it on if not already on, which should be on regardless if you are traveling.
Select after one minute or after 5 minutes for require password. A shorter time for require password is more secure.
Turn Erase Data on. All iPad data will be erased after 10 failed Passcode attempts in the event your iPad is lost or stolen.
Any computer can be hacked. Passwords can be bypassed.
I would reduce the amount of sensitive information on your iPad to the absolute minimum.
According to media reports, law enforcement officials (who can sometimes also be criminals) have tools to hack into handheld devices.