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