Bottle slots in lunch boxes are a kid thing, and that's fine

A dedicated drink bottle compartment helps with packing if the lunch box is for a kid—it keeps the bottle upright and keeps the rest of the food from getting squished.

Most kids’ insulated lunch bags have an external mesh pocket on the side that’s exactly bottle-sized. Wildkin, Skip Hop, and Pottery Barn Kids all do it. Some bento-style boxes use an elastic loop inside instead. That pocket genuinely helps because the bottle is usually the heaviest, most awkward thing in the packed bag. With one, you’re not trying to Tetris a sippy cup next to a sandwich.

The downside is flexibility. The slot is fixed, so if you don’t pack a bottle, you’ve lost that space. Wide bottles might not fit, and the bag gets a little bulkier. For adults, I’d skip it—just carry your water bottle separately.

If the bottle leaks, the slot won’t save you—but it can keep the leak from ruining the sandwich.