- Suunto M-3 D/L Compass One Size - $43.00
- Be Expert with Map and Compass - $8.99
- Outdoor Survival Compass - $8.99
- CMMG Official US Military Tritium Lensatic Compass - $71.00
- Ranger Pacecounter - $5.99
A 3D compass isn't so much an invaluable outdoor tool as it is a nifty demonstration of physics and Earth's magnetic field. Don't get me wrong, it might be the most accurate compass you'll ever use. But being made of neodymium magnets encased in a domed glass housing, this 3D compass is better suited as a decorative paperweight or gift for a geek than a must-have addition to your survival gear.
In addition to its very un-compass-like appearance, the 3D compass doesn't behave in the way a traditional 2D compass would. If you use it in the northern hemisphere, the 3D compass points both north(ish) and down to the ground. That's in response to the earth's magnetic field - the compass follows the flux in 3 dimensions, just like birds.
If you're a traveler up for packing a 3D compass instead of a garden gnome, you'll notice that near the equator the poles become horizontal, so the compass will no longer point down. And in the southern hemisphere, it will be the South Pole that points down.