Apples Float Because They Are 25% Air

The playful buoyancy of an apple in a tub of water is a direct result of its unique internal structure. A surprisingly large portion of an apple’s volume, roughly one-quarter, isn’t fruit (Review) pulp at all, but tiny pockets of air. These pockets, known as intercellular spaces, are the gaps between the fruit's cells. This trapped air makes the apple significantly less dense than water, causing it to float effortlessly on the surface. These same air pockets are also responsible for the crisp, satisfying snap you hear and feel when you bite into a fresh apple, as the pressure from your teeth ruptures the cellular structure and releases the trapped air.

This natural flotation has been part of human tradition for centuries, most famously in the game of apple bobbing. The practice is thought to have origins in a Roman festival honoring Pomona, the goddess of fruit trees, which later merged with ancient Celtic traditions associated with the festival of Samhain. Without understanding the precise science of density, people recognized the apple's tendency to float, turning a simple physical property into a festive ritual. So, the next time you enjoy a crunchy apple, you're experiencing the same feature that has made it a centerpiece of autumn celebrations for generations.