  Shock wave induced cavitation experiments and atomic force microscopy
measurements of flat polyamide and hydrophobized silicon surfaces immersed in
water are performed. It is shown that surface nanobubbles, present on these
surfaces, do not act as nucleation sites for cavitation bubbles, in contrast to
the expectation. This implies that surface nanobubbles are not just stable
under ambient conditions but also under enormous reduction of the liquid
pressure down to &#8722;6MPa. We denote this feature as superstability.
