The guardian farm is a rite of passage. It is one of the largest and most involved builds a survival player takes on, and it pays back in bulk: prismarine and prismarine bricks for building, sea lanterns for lighting, raw cod for food, and some of the highest XP throughput of any farm in the game. If you have ever wanted an endless supply of that blue-green stone, this is how you get it.
It is also the most ambitious farm on this site, so this guide is honest about the scope. A guardian farm is built inside an ocean monument, and monuments are big, dark, and defended. The build is worth it, but plan for a real project.
Everything here targets Minecraft 26.3 Java Edition. This is a spoke of the farm guides hub, and it leans on the same spawn fundamentals as the general mob farm guide.
RateNo published prismarine/hour figure; scales with cleared monument area
XP level10 XP per guardian, 10 XP per elder guardian
Build timeMulti-session build: drain or funnel an entire 58x58-block monument
DifficultyAdvanced
Who this is actually for
Be honest about this one before anything else: a guardian farm is the single biggest build category on this site, and most players should not start one as their first automated farm. It means locating and mapping an entire ocean monument, killing three fixed, dangerous mobs while fighting a debuff that cripples your mining, then either draining a huge volume of water or precision-tuning underwater flow, before a single spawn platform exists. It is a multi-session project, sometimes a multi-week one solo.
This guide is for players who already have a base and decent gear, and specifically want an ongoing, renewable supply of prismarine-family blocks, or the best sustained XP grind available without a spawner. If you mainly want XP quickly, a spawner-based mob farm (see the general mob farm guide) is far smaller work. If you want prismarine once, mining the monument's existing blocks by hand gets you a full inventory in an afternoon, no farm required. Build the farm when you want both outputs indefinitely and are willing to spend the time.
What a guardian farm produces
- Prismarine, prismarine bricks, and dark prismarine, the monument's signature building blocks, in large ongoing quantities as guardians die and monument blocks are mined.
- Sea lanterns, crafted from prismarine crystals and shards, a strong decorative light source.
- Raw cod (and occasionally other fish), a renewable food source from regular guardian drops.
- XP at 10 per guardian and 10 per elder guardian, which is notable specifically because it comes from a mob that spawns in a very large, dense volume rather than a single spawner box: the XP rate is a function of how many guardians you can cycle through per minute, not a fixed per-kill bonus higher than other mobs.
The monument is the farm: spawn volume rules
Guardians have a spawning restriction that makes this whole build possible and explains why you cannot put a guardian farm anywhere else: they spawn only in water within the ocean monument structure itself. Dig a room somewhere else and fill it with water and nothing spawns; the game only considers guardian spawns inside the monument's own footprint.
An ocean monument's base footprint is 58 by 58 blocks, roughly 3,364 square blocks of spawnable water volume. That is what makes the yields so high once the build is finished: unlike a mob-spawner farm limited to a small fixed box, the monument hands you a huge spawn volume for free. The tradeoff is that volume starts out full of water and stone, which is the multi-session digging and draining problem described above.
There is no way to relocate or shrink this requirement. The spawn region is fixed to the monument's generated structure. Any farm design, drained or not, has to work within that same footprint.
Draining vs not draining: the two real approaches, honestly costed
- Drain and platform. Pump or bucket out the water across the entire monument volume (commonly with sponges, which absorb water and can be dried and reused in a furnace), then build a flat spawn platform with a central drop into a kill chamber. This gives the cleanest, most predictable spawns, since guardians can only spawn on your platform once nothing else in the structure holds water. The honest cost: draining a 58x58 footprint through multiple levels is one of the largest block-moving jobs in the game, and it has to happen before the farm produces anything at all.
- In-place funnel. Leave most of the original water in place and use bubble columns, water flow, and block placement to guide guardians that spawn throughout the structure toward one collection point. Less raw digging, but a much fussier tuning process: spawns compete across the whole undrained volume rather than concentrating on a platform you control, so throughput is generally lower and harder to reason about than a drained build.
Neither is "the wrong way." Drain-and-platform trades a huge time investment up front for the best long-term rate; in-place funneling trades a lower ceiling for a build you can start producing from sooner.
Elder Guardians: fixed positions and Mining Fatigue
Every ocean monument generates with exactly three elder guardians, and their positions are fixed by the structure itself: one in the top room, and one in each of the monument's two wings. They do not respawn once killed, and they do not move to a different monument; killing the three that exist is a one-time task per monument.
The reason you cannot skip this step is Mining Fatigue. In Java Edition, each elder guardian applies Mining Fatigue at amplifier level III to every survival-mode player within a 50-block radius, reapplying roughly every 60 seconds for as long as any elder guardian is alive nearby. That effect reduces attack speed by 30% and cuts mining speed far more severely, to the point that breaking even soft blocks like sand takes an impractical amount of time. Trying to dig out a monument while an elder guardian is still alive nearby is not just slow, it is close to unworkable.
Two ways players deal with it:
- Drink milk to clear the effect immediately, then get back to work until the elder guardian reapplies it (roughly every 60 seconds if you're still in range), which works as a stopgap while you're still hunting the three down.
- Kill all three elder guardians first, which permanently removes the Mining Fatigue source for that monument. This is the approach every serious build eventually needs, since digging out an entire 58x58 structure under a recurring debuff is not realistic.
Elder guardians have 80 health and hit hard (their laser deals 8 damage plus 4 magic damage on Normal difficulty, and their spike defense punishes melee attackers for 2 to 3 damage per hit), so go in with Water Breathing and Night Vision potions and decent gear, not bare-handed.
Guardians in general fire a laser that takes 4 seconds to charge, deals 6 damage plus 2 magic damage on Normal difficulty, has a 15-block range, and cannot be dodged once it locks on. Elder guardian lasers hit even harder. Bring Water Breathing and Night Vision potions (see the brewing guide), keep milk on hand for Mining Fatigue, and prioritize the three elder guardians before any serious digging.
Building it (the realistic path)
- Locate a monument and mark its exact 58x58 bounds. The guardian spawn region is tied to where the monument generated, so knowing the real corners matters before you plan a platform.
- Kill the three elder guardians. One in the top room, one in each wing. Until all three are dead, Mining Fatigue within 50 blocks of any survivor makes real building impractical.
- Choose a design. Drain-and-platform for the highest ceiling at the largest time cost, or in-place funnel for a faster but lower-throughput build. See the honest comparison above.
- Kill and collect. Guardians fall or are pushed to a chamber where you kill them (drop damage, a lava blade behind glass, or manual hits), with hoppers feeding chests below.
- AFK spot within normal spawning range of the monument so spawns keep running while you collect.
Because of the scale, many players build a guardian farm as a server project, splitting the drain or the elder guardian kills across sessions or people. If large water builds and constant chunk loading are straining your world, a stronger host helps; the server admin guide covers keeping big farms performant.
| Approach |
Setup cost |
Spawn cleanliness |
Best for |
| Drain and platform |
Very high: full structure drain, then a built platform |
Best: spawns land only where you want |
Players committed to a long-term, max-rate farm |
| In-place funnel |
Lower: bubble columns and flow, minimal draining |
Lower and fussier to tune |
Faster results, smaller time budget |
Pros
- The monument's own footprint hands you a large fixed spawn volume for free, far bigger than a typical spawner box
- Produces four different useful outputs at once: three block types, food, and top-tier XP
- Elder guardians are killed once per monument; Mining Fatigue is not a recurring problem after that
Cons
- Among the largest single builds in the game; realistically a multi-session project
- No published items-per-hour or XP-per-hour figure exists, so you cannot know your exact rate until it's built
- The drain-and-platform approach, which gives the best results, is also the most labor-intensive option in the guide
Common mistakes
- Not killing the elder guardians first. Mining Fatigue at amplifier III within 50 blocks will make serious digging impractical. Clear all three before committing to the drain or platform.
- Ignoring the spawn region bounds. Guardians only spawn within the monument's own generated structure, roughly 58x58 blocks; build your platform inside those real bounds, not an approximation.
- Leaving stray water and dark caves nearby. Other spawnable water and unlit caves near the monument steal spawns and mob cap from your platform. Light or seal them.
- No Water Breathing or Night Vision. The build phase underwater without potions is slow and dangerous even before guardians get involved.
- Underestimating the drain. Treating a 58x58 footprint like a small pond. Budget real time, sponges, and inventory space for a structure that size.
Rates and optimization
The wiki does not publish an items-per-hour or XP-per-hour figure for a guardian farm; actual throughput depends entirely on how much of the spawn volume you've cleared for guardians, how quickly your kill chamber processes them, and how well you've suppressed competing spawns nearby. Treat any specific hourly number you see elsewhere as an estimate for that build, not a guarantee for yours. What is fixed is the per-kill numbers: 10 XP per guardian and 10 XP per elder guardian, with prismarine shards, prismarine crystals, and raw fish base drop rates that Looting raises, since Looting increases the maximum quantity rolled for each of those drop categories.
To maximize a finished farm:
- Eliminate every competing spawn spot in and around the monument so all spawns concentrate inside your controlled volume.
- Kill guardians fast so the mob cap never stalls new spawns from appearing.
- Use a Looting-enchanted weapon to raise prismarine shard, crystal, and fish drop quantities per kill.
The result, once actually finished, is a large ongoing supply of prismarine-family blocks and sea lanterns plus one of the best sustained XP sources in survival, at the cost of being the largest build most players will ever finish.
The monument is not a location you build a farm near. The monument's own footprint is the farm.
Frequently asked questions
Where do guardians spawn for a farm?
Guardians spawn only within the water inside the specific ocean monument structure that generated, a footprint roughly 58 by 58 blocks. That fixed volume is why guardian farms are built inside monuments and nowhere else, and why the yields are large once the volume is under your control.
Do I have to kill the elder guardians?
Yes, before serious building. The three elder guardians, one per monument wing plus one in the top room, apply Mining Fatigue at amplifier III within 50 blocks, reapplied roughly every 60 seconds, which makes breaking blocks far too slow for a build this size. Kill all three first; milk clears the effect temporarily if you get hit again before they're dead.
Do I need to drain the ocean monument?
Not strictly. Drain-and-platform gives the cleanest, highest-ceiling spawns but costs the most labor. In-place funnels use bubble columns and water flow with less draining, at the cost of lower, fussier throughput. Different tradeoffs of time versus rate, not a right and wrong answer.
Is a guardian farm worth it?
If you specifically want an ongoing supply of prismarine-family blocks, sea lanterns, renewable fish, and one of the best sustained XP rates in the game, yes. If you just want prismarine once, mining the monument by hand is much less work. This is a build for players ready to commit real time, not a quick project.
Does Looting affect guardian farm drops?
Yes. Looting raises the maximum quantity rolled for prismarine shards, prismarine crystals, and raw fish drops from guardians. It does not change the fixed 10 XP per kill, which is unaffected by Looting.
A guardian farm is an endgame trophy: the blocks, the lighting, and the XP together, for players who have already decided it's worth the time. When you are ready for a project this size, the farm guides hub has the rest of the farms that lead up to it, and an enchanting setup turns all that guardian XP into gear.
