Hand Held or Mounted?
There are two options available, either a Hand Held GPS which is perfect for bush walking and a Mounted Unit which is designed for boats, kayaks and fisherman.
Colour Or Black & White?
Black & white units are cheaper in price and are great if you don’t intend to use it all the time. They show a basic black & white image. Colour units are a lot clearer and easy to read. They can show you the different terrain, water depth, land colour and much more.
2D Or 3D?
Both 2D and 3D maps will show you all the information you need, whether on land or at sea. However the newer 3D imagery makes it a lot easier to distinguish the depth and height of certain terrains.
Screen size varies from unit to unit. A larger screen will obviously be easier to read, but may be too large to hold while trekking or mounting in a boat.
You will require a certain mapping card for your particular unit. For example, Garmin hand held units require Garmin TOPO Australia and New Zealand maps. Lowrance marine GPS mounted units require a Navionics card.
Storage of Waypoints
Most GPS units whether hand held or mounted units will allow you to mark waypoints. This is ideal for a lot of uses and will allow you to set a course based on the waypoint marked.
Make sure you are in an open area when using the GPS, as it requires a clear path to gain a signal.