Here's Why Your Cooler's Lid Is Actually Hollow

If you have a cooler, you might have noticed that the lid is hollow. But have you ever wondered why this is so?

Courtesy of Decide Outside, we now know that cooler lids rely on an air gap for insulation. This is more common in cheaper coolers, as the hollow lid allows the manufacturer to cut costs and skip the insulating foam. (Pricier coolers, on the other hand, are more likely to have insulating foam on ​all​ sides, including the lids.)

With that being said, many folks are under the impression that hollow lids are meant to be filled with water and frozen. This is partly due to a round piece in the lid that's easily removable. For example, in a TikTok video, @sidneyraz uses a screwdriver to pop out the piece, which exposes a hole.

sidneyraz/TikTok

This isn't true, though. As many users note on TikTok, if you were to fill the lid with water and freeze it, the water will expand. This could potentially break the plastic lid. Not to mention, if the lid was filled water and frozen, the cooler will be super heavy.

So what's the deal with the hole? It's actually part of the manufacturing process. According to a TikTok user who creates similar parts for work, the hole is for an air tube. While the plastic is in the mold in the oven, the air tube allows air to flow out. The more you know.

Bottom line: The hollow lid and hole are standard parts of the manufacturing process, so they aren't necessarily meant to be altered. Some people do like to fill the lid with spray foam for extra insulation, but this should be done with caution. (Decide Outside has a great guide right here.)

Whatever you do, ​don't​ fill your cooler lid with water and stick in the freezer. Safety first, kids!