Minecraft wiki entry for Beginner%27s_guide, associated text: You have no problems if you have just spent your night in a cave. If you haven't, the easiest way to do so is to roam the Overworld a little and look out for exposed cave entrances. Mountains biomes have caves inside mountains, but these are generally not what you want, because only coal ore appears above sea level. For iron and better ores, you want to find a cave opening into the ground (these are quite common) and head downward. Sometimes such caves end immediately, but often they continue into big cave systems. If they seem to end right away, sometimes there is a continuation about 2-8 blocks farther back and below the cave's end; mining in these directions (8 blocks back and down, exploring somewhat to the sides) can reveal this if it is the case. Digging away gravel or dirt can also expose cave extensions, but you may go through a few shovels that way. If you can't find any all day, just sleep away the night, replenishing your resources like wood and food as you use them. If you hear suspicious, hostile noises, just try to listen and follow them.