Swim in the sea
Whilst Kep beach doesn't have the world's nicest sand, it's still enjoyable to go for a swim in the calm, cool water, as lots of Cambodian kids do every day! There are wooden lounge chairs spread along the beach, occasionally with a Cambodian woman requesting $1 to use them. Lots of cold drink vendors nearby and a decent place to watch the sunset too. Don't believe the gloom and doom that some guide books write about the beaches in Kep, they're actually quite nice.