Forces have also been told people who need a ‘cooling-off’ period after rows at home can move between households if they leave for several days.
But people who sit on park benches for too long are likely to be breaking coronavirus lockdown rules.
Guidance issued to forces in England also indicates people should not be working from nearby parks rather than their home.
However stopping to rest or have a picnic while on a long walk and buying luxury items and alcohol are all likely to be considered "reasonable", according to the advice given to officers.
It comes after some 3,203 fines were handed out by police in England between March 27 and April 13 to those considered to be flouting the rules.
The guidance issued by the National Police Chiefs' Council (NPCC) and the College of Policing (CoP) gives more advice to officers on how to interpret the lockdown restriction laws - known as the Health Protection (Coronavirus, Restrictions) (England) Regulations 2020.
The legislation gives them powers to fine those in breach.
Details of the document emerged on Thursday after it was issued to forces last week amid concerns some officers were misunderstanding the new powers.
Described as a reproduction of a ‘really useful practical guide’ from the Crown Prosecution Service (CPS) on what might constitute a reasonable excuse, it warns the list of examples is ‘not exhaustive’ and ‘each case still needs to be considered based on the individual facts as they present themselves’.
It adds: ‘Some public statements made soon after the adoption of the regulations suggested that members of the public could only leave their homes if 'essential' to do so.
‘However, this is not the test set out in the regulations and there is no legal basis for a requirement in those terms to be imposed.’
This guidance follows the previously announced lockdown measures including staying at home and only go outside for food, health reasons or work (but only if you cannot work from home). If you go out, stay 2 metres (6ft) away from other people at all times.
Wash your hands as soon as you get home. Do not meet others, even friends or family. You can spread the virus even if you don’t have symptoms.
Here’s what the police guidance says:
What you can do
- buying luxury items and alcohol
- driving to the countryside and walking, when far more time is spent walking than driving
- stopping to rest or eat lunch while on a long walk
- exercising more than once a day
- moving to a friend's address for several days to allow a "cooling-off" following arguments at home
- buying tools and supplies for repairs and maintenance.
What can’t you do
- a person who can work from home choosing to work in a nearby park
- a short walk to a park bench when the person remains seated for a much longer period
- buying paint and brushes simply to redecorate a kitchen
- driving for a prolonged period with only brief exercise.
A CoP spokeswoman the information was put together so officers and the CPS are ‘joined up’, adding: ‘This isn't new national guidance and the messaging for the public hasn't changed.’