public static void startDefaultNavigationApplication(final int defaultNavigation, final Activity activity, final Geopoint destination) {
        if (destination == null) {
            ActivityMixin.showToast(activity, CgeoApplication.getInstance().getString(R.string.err_location_unknown));
            return;
        }

        navigateGeopoint(activity, destination, getDefaultNavigationApplication(defaultNavigation));
    }
Starts the default navigation tool if correctly set and installed or the compass app as default fallback.
main/src/main/java/cgeo/geocaching/apps/navi/NavigationAppFactory.java