We report the irreversible structural failure of individual multiwalled carbon nanotube (MWNT) tips after water submersion. We used 11 individual MWNTs with varying geometries and showed length dependent MWNT failure with scanning electron microscopy. Shorter MWNTs are more likely to survive penetration of the water-air interface. We observed the bending of MWNT probes on the water surface using optical microscopy. Surface tension force acting on MWNTs at the water-air interface was calculated. Compared to shorter MWNTs, the calculations suggest that longer MWNTs exert a smaller bending restoring force with respect to surface tension force, leading to MWNT bending until failure.