In article ,
says...

Liquid helium is considered a super-fluid inasmuch as it climbs walls and will go through molecular-size openings.

Peter Wieck
Melrose Park, PA

That is if you reduce the pressure by pumping until the temperature
drops to below about 2°A (see
https://en.wikipedia.org/wiki/Superfluid_helium-4). I remember doing
this and seeing the helium stop boiling energetically and go unnaturally
calm. It was still boiling, of course, because heat was still leaking
in...

Mike.