Minecraft wiki entry for The_Void, associated text: Dig a hole up to the bedrock;
Find three bedrock blocks in a line at height 127, the highest layer of bedrock (you can press F3, point to the bedrock and check the second number on the "Looking at" line). The first block must have two air blocks below it: the player needs to go there. The second and the third bedrock blocks must have an air block below them and another bedrock block below the air;
Teleport with an ender pearl below the third block: you will suffocate in the bedrock;
Jump and throw an ender pearl on the top of the Nether: you arrived.