Next time they get into the pantry, close the door, turn out the light and block the door. After a couple hours, let them out and they will never go near your pantry again!!

There are dozens of safety latches designed to keep kids out. All are a pain in the butt to some extent. just look themn over and decide how much nusance you can live with.

IKEA has a 1 x 1 1/2" flip-down combination lock (3-number) for drawers. It could be turned sideways and used on the door.

Don't know if you can still buy them but I used plastic things that fit over each doorknob, my son figured them out after awhile but I just put a thick rubberband over it to tighten it up so he couldn't get his fingers under it to open it. They are plastic just bit larger then doorknob with pieces that get smaller as they get closer to the door- there are 5-6 slits & adults can slip finger under & open door. A rubberband like type around big bunch of broccoli works great! Don't lock your kid in a dark room- great way to have a kid distrust you for life- act like an adult & loving parent!

A simple hook and eye installed up at the top of the door should be out of reach.

Even one of these from Home Depot mounted up high at the top of the door should work.

When my twins were little, I secured all the bathroom and kitchen cab doors and drawers with magnetic activated catches. Nothing mars the exterior of the door and by placing a magnet near the position of the latch, the tongue retracts, allowing the drawer or door to be opened. Super slick since it won't mar the exterior when someday you no longer need them. The twins are big now and I just recently removed them, in case anyone wants to buy them. You can get them at HD too but pricy, especially if you are looking to do a whole kitchen or house.

These magnetic latches are what I used.

Invisible from the outside, so there's no visible lock to tempt the kids into trying to undo.

They do work on large and small doors.