It's a long walk usually for exercise or pleasure
go hiking / hike
to participate, to take part in
join in
to spend time with (friends)
hang out with
to stay in good physically condition
keep fit
It's an area where people can stay in tents for a holiday
campsite
to sit or lie in the sun in order to make your skin darker
sunbathe / sunbathing
visiting interesting places; touring: We did some sightseeing in Paris.
sightseeing