A nominally floorless hikers' shelter having a raised, tensioned waterproof canopy supported off the ground by pole supports at the front and rear, in which the canopy has a catenary curved ridgeline tensioned between a higher vertical front arch support and a lower, outwardly-angled rear arch support. The shelter is longitudinally tensioned through front and rear awnings extending from the front and rear arch supports. The front awning includes a novel guyline tensioning and ventilation structure in which spaced parallel guylines are attached to the awning at circumferentially spaced locations between the arch support and the lower edge of the awning, leaving an unbroken web of fabric tensioning the arch, and allowing lower portions of the awning to be selectively rolled up for ventilation. The shelter preferably has a hanging insect netting perimeter, including front and rear door panels and sidewalls.