Minecraft

To construct a nether portal you will want a diamond pick axe. You need 10 blocks of obsidian which is obtained where lava meets water. If you don't have a diamond pick you can use buckets of lava and water to form the obsidian but this is tricky as you won't be able to move it. The shape of the portal is as follows. Place two blocks side by side on the ground. On either side of these obsidian place a placeholder block such as dirt. Then on top of the dirt place three blocks of obsidian straight up and then another dirt. Do this on both sides. Then place the remaining two blocks of obsidian in between the dirts on the top. Light the portal using a flint and steel which is made from one iron and one flint.

Create a world using this seed: -1768198259

As soon as you spawn you'll see a broken Nether portal, look behind the Nether portal and take the Obsidian, Golden Pickaxe and Flint and Steel from the chest.

Break the Crying obsidian and replace it with regular Obsidian, place the 3rd Obsidian block above the last one you placed, grab some blocks nearby and place them on the corners of the nether portal, place the last 2 Obsidian blocks in the middle, ignite the portal and enter. The achievement should unlock shortly after.