here in the US you can descend below the minimum altitude only in emergencies or when attempting to land.
FAR 91.119 is the applicable reg. There is nothing to stop you flying for miles at 1 foot AGL over a nice smooth patch of desert as long as you stay 500ft from any 'person, vessel, vehicle or structure'.
If you decide to do something as recklessly enjoyable as this, you should always maintain and be pushing against some 'up trim', just in case your hand slips off the stick. Also be careful when you turn, lest you drag a wingtip.
Or so I have been told
