  Alfv\'en waves (AWs) are inevitable in space and astrophysical plasma. Their
crucial role in various physical processes, occurring in plasma, has triggered
intense research in solar-terrestrial physics. Simulation studies have proposed
the generation of AWs along the surface of a cylindrical flux rope, referred to
as Surface AWs (SAWs); however the observational verification of this distinct
wave has been elusive to date. We report the first \textit{in-situ} observation
of SAWs in an interplanetary coronal mass ejection flux rope. We apply the
Wal\'en test to identify them. The Elsa\"sser variables are used to estimate
the characterization of these SAWs. They may be excited by the movement of the
flux rope's foot points or by instabilities along the plasma magnetic cloud's
boundaries. Here, the change in plasma density or field strength in the
surface-aligned magnetic field may trigger SAWs.
