Growing carbon nanotubes (CNTs) by arcing from graphite electrodes does not demand a noble gas atmosphere: water will do! CO and HZ bubbles generated by reaction of C vapor with water provide a quasi-inert atmosphere in which multiwalled carbon nanotubes grow from the cathode. Using cobalt salt solutions instead of plain water, the authors obtained CNTs filled with metallic cobalt and elemental sulfur (see Figure), potentially useful as nanoprobes for magnetic force microscopy.