How to Make a Sea Lantern in Minecraft: The Ultimate 1.21 Guide

I remember the first time I tried to build a base at the bottom of a deep ocean biome. Everything was pitch black, and the standard torches I brought just kept popping off. That was my first introduction to the sea lantern, and honestly, I have never looked back. These are not just the brightest light sources in the game, they are also some of the cleanest looking blocks you can find for a modern or futuristic build.

In this guide, I will show you exactly how to craft them, where I go to find them naturally, and some of the technical secrets I have picked up over years of raiding ocean monuments. We are even going to look at how the new 1.21 Crafter block changes the game for infinite light.

How to craft a Sea Lantern in Minecraft

If you are like me and prefer to stay away from the scary guardian lasers as much as possible, you will probably want to craft your lanterns at home. You will need a crafting table and two specific materials that only drop from the guardians that live in ocean monuments.

To make a single sea lantern, you need:

• 4 Prismarine Shards
• 5 Prismarine Crystals

When you open your 3×3 crafting grid, I have found that the easiest way to remember the pattern is to think of a cross. You place your 4 prismarine shards in the four corners of the grid. Then, you fill in the remaining five spots with your prismarine crystals to form a plus sign or a cross in the center.

I should warn you that getting these materials manually is a bit of a grind. In my experience, a guardian has a 40 percent chance to drop a crystal and a 40 percent chance to drop a fish, with a 20 percent chance of dropping nothing at all. If you want to be efficient, I highly recommend using a sword with Looting III. This enchantment can increase your maximum shard drop to 5 and your crystal drop to 4 per kill.

Where to find Sea Lanterns naturally

Sometimes crafting is too slow, and you just want to grab what nature has provided. I usually find sea lanterns in two main places:

• Ocean Monuments: These are the massive, pyramid like structures guarded by guardians. You will find roughly 100 lanterns scattered throughout the various rooms of a standard monument.
• Ocean Ruins: These are smaller, often crumbling structures. They don’t have as many lanterns, but they are much easier to raid early in the game.

If you are struggling to find a monument, I suggest visiting a cartographer villager and leveling them up to a Journeyman. They will sell you an ocean explorer map that leads you right to one. I have also found that monuments generate on a very predictable grid. The math for the center of a monument usually follows this formula:

X = (n x 512) + 200

Z = (m x 512) + 200

If you know how to turn on and use coordinates, you can use this grid logic to find your next monument without spending a single emerald.

Pro tips for harvesting without breaking things

One mistake I made early on was trying to mine sea lanterns with a regular pickaxe. If you do that, the block will shatter and only drop 2 or 3 prismarine crystals. You will lose the shards and the lantern itself, which is a huge waste of resources.

• Always use a tool with Silk Touch: This is the only way to pick up the block itself.
• Use Fortune III if you must break them: If you don’t have Silk Touch, using Fortune III can increase the crystal drop to a maximum of 5, but you still lose the shards.
• Clear Mining Fatigue first: Elder guardians will hit you with an effect that makes mining almost impossible. I always bring milk or kill the three elder guardians in the monument before I start my harvesting run.

Advanced spawning logic: Java vs Bedrock

I have spent a lot of time testing farms on both versions of the game, and the way guardians spawn is totally different. This is crucial if you are planning to build a farm for infinite lanterns.

• In the Java Edition, guardians can spawn in any water block within the monument’s 58x58x23 bounding box. I have found that covering the top of your farm with solid blocks is a must, because 95 percent of spawn attempts will fail if the water has a direct view of the sky.
• In the Bedrock Edition, guardians only spawn in 25 specific vertical columns. They don’t care about sky access, but they are very picky about exactly where those columns are located.
• Redstone transparency also varies: On Bedrock, redstone signals can travel both up and down through sea lanterns. On Java, they can only go up, just like with glass or slabs.

Using the 1.21 Auto Crafter for infinite light

The 1.21 Tricky Trials update was a total game changer for me. I used to spend hours manually clicking through the crafting grid to turn my farm drops into lanterns. Now, we have the Crafter block.

Automating sea lanterns is a bit tricky because the recipe isn’t homogeneous. Since you need 4 shards and 5 crystals, a simple hopper will eventually clog the machine. I found that the best way to handle this is to use a 20 game tick clock. This speed is stable enough to keep the inputs balanced.

You will need a redstone system that ensures the shards only go into the corners and the crystals only hit the center. Once you get it working, a dual monument farm can push out over 100,000 items per hour, giving you more lanterns than you will ever know what to do with.

The mysterious lore behind the light

I love digging into the history of these blocks. There is a lot of evidence in the game suggesting that guardians were actually built, not born. While Mojang has shown concept art of elder guardians with bones, many players still believe they are ancient machines created by a lost civilization.

I have noticed that ocean monuments are almost always found near ruined villages. Some lore experts think that the ancient builders were forced underwater by some disaster and built the monuments as a way to protect their gold and their conduits. The sea lanterns were likely their only way to see in the deep dark, using the bioluminescent crystals they harvested from their guardian sentinels.

It makes sense when you see how lanterns are needed to power a conduit, which is what allows you to breathe underwater indefinitely. If you are also interested in aquatic life, you might want to learn how to get and pick up turtle eggs to add even more life to your underwater base.

Is it better than Glowstone?

People always ask me if they should stick with glowstone or go through the trouble of getting sea lanterns. It really comes down to the vibe of your build.

• Sea lanterns provide a cold, clinical, or even divine feeling. They look amazing with quartz and concrete.
• Glowstone feels much warmer and more inviting, but the texture is very busy and can look a bit messy in a clean build.
• Froglights are a great middle ground for pastel colors, but sea lanterns remain the king of modern design.

Both sea lanterns and glowstone emit a light level of 15, so you aren’t gaining any extra brightness by picking one over the other. It is all about that aesthetic.