A portable location alarm device is provided which allows a user to preset an alarm event to occur when the device arrives at a pre-determined location. The alarm event alerts the user by audible, visual or vibrating means. The alarm device determines it's actual location using GPS data. In one embodiment the user bookmarks particular locations while physically present at a given location. Part of the bookmarking process involves the device simultaneously receiving GPS data that describes the physical location. The user can subsequently set an alarm event for any bookmarked location without the need for the device to carry large databases, for example of the type cross-referencing place names to mapping co-ordinates.