The Science Behind This Crazy Water Trick 💧

Added: 2026-06-03

[00:00:00]Have you ever wondered why some objects float on water effortlessly while others sink straight to the bottom? It all comes down to a simple scientific principle called density. Let's break it down with a simple visual experiment.

[00:00:13]When we pour water into a clean empty glass, we are creating our baseline.

[00:00:17]Water has a specific density and anything placed inside it will react based on its own weight and volume. 025 to 033. First, let's test a lightweight plastic bottle cap. As we gently place it on the surface, it floats instantly.

[00:00:33]Why? Because the plastic cap is far less dense than the water beneath it. 035 to 043. Next up is a dry erase marker. Even though it's larger and heavier than the cap, it still manages to stay afloat horizontally on the surface. The air trapped inside the marker keeps its overall density low. Now, what happens if we try a larger empty plastic water bottle? It mimics a boat. Because it's mostly filled with air, it displaces enough water to float perfectly.