USING YOUR GPS OR GOOGLE/MAPQUEST DIRECTIONS
Going to a swimming hole is not like going to a Starbucks - (especially if there is a hike involved, of course) but even if there is not much of a hike, there is info you need about where to park - how to walk when you leave the parking area (avoiding private property, for instance) - whether to walk upstream or down when you hit the water - safety issues - etc. etc. All this info is in the DIRECTIONS part of the web site listing.
GPS TYPES AND USAGE - GENERAL INFORMATIONWe are not experts on GPS usage but we have learned a few things that we might share with you:
TYPES AND TIPSThere are basically two types of GPS units we are concerned with - those for DRIVING use and those for HIKING use.
The AUTO use ones use a road map, the HIKING use ones usually use a topo map. The better auto ones will speak the street name for each turn (called "text to speech") - others just say "Turn left in 500 feet" - we strongly recommend that you get the text to speech (TTS) feature.
If you get a driving one for going to swimming holes, we suggest that you make sure that you can input 1) individual latitude/longitude points and, 2) a file of many latitude/longitude points (often called "Points of Interest" or POIs). Also, make sure it includes unpaved roads in National Forests, National Parks, BLM lands, etc..
If you get a hiking one for going to swimming holes, make sure you can input a file of latitude/longitude points (called "Waypoints") - the cheaper ones dont have data file inputs, you have to key in each point. Also, on the hiking ones, make sure you get a high sensitivity receiver - usually this is the SIRF chipset. Under trees or clouds, this will allow you to still get a signal.
STANDARDS AND FORMATS
There are two poular North American Datum (NAD) standards you will see in these units and it DOES make a difference which one is being used. NAD27 is the older one used by the USGS topo maps for many years and is the one we use in the swimming hole listings. NAD83 is a newer standard (appreantly more consistent internationally). Hiking GPS units usually are switchable between these and so you can use either. Auto GPS units seem to use the NAD83 and are NOT switchable.
There are also several different data formats for the latitude/longitude files you would input to these devices. The hiking ones tend to use the GPX format and the driving ones seem to use a variety of formats, including the GARMIN, KML (used also by google earth) and others. The basic information in all of these is very simple - just the altitude, longitude and a name/description of each point.
CONVERSIONS AND MAPS
Hopefully, there will emerge more standardized formats in the near future, but in the meantime there are some web resources to help make these conversions.
NADCON - To convert between NAD27 and NAD83.
GPS BABEL - To convert between data formats (.txt, GPX, KML, GARMIN, Magellan, etc)
GPS VISUALIZER - To convert files AND produce maps (google maps, google earth maps, etc)