Layers and Tracking Layers Unlike the Overworld, the Nether has three main layers. The top, the bottom, and the middle.
The bottom layer is located around a depth of 30.
The middle layer is located around 60-70, similar to the Overworld.
The top layer is finally located around 90.
Layers would theoretically make the Nether more easily navigable, but they don't.
Why not? Because the Nether is full of large gaps and lava.
Gaps are in a sense, lakes and oceans made out of air. The bottom layer has an "ocean" of lava, whereas the top and middle layers just have big gaps, making navigation through the Nether extremely dangerous.
Here is an example of a gap.
Luckily, each layer has some paths of accessibility between the layers every once in a while.
Also, the safest way of getting around the Nether is to mine underneath the bottom layer. It is not recommended because it is extremely slow, and one also must be careful of the lava lakes above.
Lava lakes on the bottom layer usually range from 10 to 20 blocks in depth, but can be smaller/larger.
There are a few easy conversion formulas for the Nether:
To convert Overworld coordinates to Nether coordinates:
Overworld coordinates / 8 = Nether coordinates
To convert Nether coordinates to Overworld coordinates:
Nether coordinates x 8 = Overworld coordinates
This makes long distance Overworld travelling a lot easier through the Nether.
To read coordinates press F3 on a Windows. I'm not sure what it is on a Mac, but I think it is COMMAND + F3.
There aren't very many things I have to say about tracking, because I've already mentioned most you need to know.
My first tip is that sometimes it is much better to go the long way rather than try to take a shortcut.
My second tip is that sometimes 1x1 bridges are necessary, and when built, it is recommended to sprint across them carefully. When building them, watch out for ghasts, as they may spawn near you. Also, back up to safe ground every once in a while just in case. My last pointer for building bridges is to always hold your sneak key, by default this key is SHIFT.
Finally, try not to stay on thin ground for long, as ghasts may appear and blow up the ground beneath you.
Dangers and Mobs Mobs
It is not recommended to hit a Zombie Pigman, as they are extremely fast, stay in groups, and are all over the Nether.
Ghasts are hated by every Nether adventurer, as they are annoying, damaging, and without a bow, are difficult to hit.
Magma Cubes are slow, but can jump extremely high, and can be difficult to hit. Large ones do lots of damage as well, so it is recommended to be extremely careful when around them.
Blazes are fairly stationary and easy to hit, but do the most damage and can easy kill. Good armor is highly recommended, and is most necessary for defeating them. Luckily, blazes are only spawnable through monster spawner blocks located in Nether Strongholds.
Strange as it may seem, mining is a large danger in the Nether, especially above the bottom layer. If one is too carefree while mining in the Nether, they can easily mine a hole and quickly fall through it, to their death. One should always stay a few blocks behind where they are mining in case of this.
Lava and Falling:
Most people know of the dangers of falling long distances and accidentally tripping into lava, so I will not go into further detail on this.
When ghasts are around, this is the top death unrelated to getting killed by a ghast. The reason for this being that ghast explosions create sudden fire, and typically explode right in front of you. Also, when sprinting, one must be careful to not suddenly walk into fire hidden from the eye.
A sword is necessary for simple defense against magma cubes, blazes, and possibly hitting a zombie pigman.
When travelling through the Nether, you will encounter many places where mining is the best way through.
Bow and Arrows:
A bow is not necessary, but is extremely useful for shooting down ghasts.
Armor is highly recommended because it will protect you from common damages in the Nether, the most common being falling.
Stacks of Blocks:
Unless you want to mine even more in the Nether, you should bring a few stacks of a simple block like cobblestone, to build bridges and over gaps.
Always bring a good amount of food, as your food bar will drop quickly while sprinting.
Water buckets are also unnecessary, but are good for making your way across lava, and down gaps without taking fall damage.