Minecraft wiki entry for Nether_survival, associated text: Carrying backup items to handle specific emergencies can take up more inventory space than carrying the minimum supplies to craft what you need as the situation arises, provided you take into account that you need to be in a safe place for the time it takes to place, or craft, a crafting table, then go through one or more steps of crafting to get what you need. For example, gravel is common in all Nether biomes except basalt deltas, so flint and steel can be crafted if that becomes necessary, provided you are carrying iron. It is unwise to bank on finding iron, as the only ways to find it are as rare loot in generated chests or by bartering. The same supply of iron serves in lieu of carrying replacement pickaxes, buckets, or weapons, but could take too long to craft into a bucket to scoop up unexpected lava. Huge fungus stems can provide logs, and thus make sticks, a crafting table, and so on, but they are not as versatile as logs from trees and could take a while to find if you're in the wrong biome. Similarly, you could rely on finding blackstone rather than carrying cobblestone, but it isn't quite as versatile and isn't as easily found as gravel. Always carry logs, cobblestone, and iron, and possibly potions of Fire Resistance. If you have a lot of iron to spare, you may want to carry it as iron blocks, and bring pumpkins or jack-o-lanterns to build an iron golem if you get mobbed.