A honeymoon is an Earth ritual which where a newlywed couple celebrate their marriage by taking a traditional trip.
In 2332, Aine McAvennie's fiancé, Mike, had arranged for a cottage on a sea shore on the planet Risa. (ST short story: "Hour of Fire")
In 2374, Worf suggested to Jadzia Dax that their honeymoon involve hiking Vulcan's Forge or mountain climbing on Andoria. Dax suggested a honeymoon on Casperia Prime. (DS9 episode: "Change of Heart")
In 2379, William T. Riker and Deanna Troi planned on having their honeymoon at the Opal Sea on Betazed. Their honeymoon, however, was delayed when the USS Enterprise-E was diverted to Romulus, while en route to Betazed. Fortunately, the two were able to make it and had an "eventful" time. (TNG movie: Star Trek Nemesis; TNG short story: "Improvisations on the Opal Sea: A Tale of Dubious Credibility")