Other bizarre sights seen by hikers include naked walkers, punctured blow-up dolls, plane wreckage, fox-hunting and even aliens.
Ian Brookes, managing director at OutdoorLook.co.uk said: “Our latest survey really has produced some extraordinary results! Sex is not something you expect to stumble upon while out enjoying the countryside and some of the sights seen by our survey respondents could be really quite intimidating.
“Although the majority of hikers will probably never come across such habits, it is interesting that the darker side of the UK’s countryside has been revealed. It brings to mind the question of whether rural areas should receive higher levels of policing to ensure the safety of walkers and hikers.”
The survey also revealed that more than 10 per cent of hikers would consider walking naked while 30% recover from a days walking by heading to the pub for a pint. Motorbikes and off-road vehicles are the biggest bugbear for hikers and almost 80 per cent of walkers would choose to have their ashes scattered in their favourite hiking spot.