Also, day-tripper has many other connotations, including sexual, as evidenced from the famous "Day Tripper" song by The Beatles :)

A day-tripper is a person who goes on a day trip somewhere. For example, someone who lives in London might go to a seaside resort such as Brighton just for the day. Day-trippers usually arrive in the morning, spend the day at the beach or other tourist attractions and then go home in the evening. Day-trippers are not generally good for the economy of an area. They are a drain on the resources of the town (litter disposal, for example) and yet bring in limited income because they don't stay overnight.

A day tripper is somebody who goes on day trips. Normally somewhere you visit for one day away from where you are staying.

runner = a person who runs writer = a person who writes baker = a person who bakes video gamer = a person who plays video games day-tripper = a person who makes day trips (trips that last one day)