The indexicality of language refers to the linkage between the language and the situation of use for determining the meaning of what is being said. In this paper I describe how a player of a location-based treasure hunt game called geocaching uses indexicality of language in creating clues when hiding treasures. Based on this account, the skill, I argue, in creating an exciting treasure depends on understanding the disjunction between the context in which the clue is first interpreted and the context in which it receives its final meaning. An interesting clue should therefore contain both a literal or conventional meaning and a situated meaning, and the situated meaning should only arise when the player is close enough to the treasure. Author Keywords Geocache, location-based computing, GPS (Global Positioning System), context, indexicality, language, field study. ACM Classification Keywords H.5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous. J.5. Arts and human...