Finally, we demonstrate that bulk nanobubbles can ubiquitously exist, even in socalled "pure" water. We illustrate that even the small amount of the trace organic contaminants dissolved in the chemically "pure" solvent is sufficient to supply the amphiphile molecules needed for stabilizing bulk nanobubbles at a typical nanobubble concentration 𝑐 ~10 /𝑚𝐿 . In real situation, there exist more sources of organic contaminants that can introduce amphiphilic molecules into the solution, which tend to stabilize bulk nanobubbles.