I found a dungeon with a skeleton spawner, and I'm trying to build a "Death-pit Experience Farm" around it.

With the help of wiki pages and youtube videos, I managed to use water to flush the mobs spawned to a tunnel. At the end of the tunnel, I'm planning to build a water elevator abusing the mob AI, hoping them to swim up 23 blocks and drop down from another pit:

L                     [ room  ]
W                     [ with  ]
L<---<---<---<---<--- [spawner]   (L=ladder, W=water, <-- stream)

Everything works fine except the mobs will not swim upwards. They get stuck at the bottom of the water elevator. (If I myself follow the stream and hold "space", I'll reach the bottom of the water elevator and swim up smoothly.) Why aren't skeleton swim up? What have I done wrong?

4 Answers 4


https://minecraft.wiki/w/Tutorials/Water_Ladder says that the water ladder no longer works (since beta 1.6.6).

You should use signs instead.

enter image description here

  • 1
    A water ladder is not the same as a water elevator :)
    – James
    Oct 23, 2012 at 16:37
  • 1
    +1: Nice diagram! What program or template is that? Oct 23, 2012 at 17:34
  • @SevenSidedDie: Hell if I knew, I just found it on Google image search and suggested it as an edit. :) Oct 23, 2012 at 18:58
  • Nice one @Martin - it looks great!
    – Rory Alsop
    Oct 23, 2012 at 18:59

Replace your ladders with signs and it should work. I usually make the up-tunnels 2x2 and alternate the corners that have water so that every level has water, but that's probably overkill and a 1x1 should work.

  • Thank you for your answer. Do you have a theory about why ladders won't work and signs probably will? I see ladders being used in many tutorials and they seemed to work for them. Oct 23, 2012 at 17:29
  • 2
    @user1032613 Ladders + water were specifically nerfed (or bug-fixed, however you want to look at it) by Mojang to prevent super-fast water elevators for player movement, and it looks like the fix affects mobs as well. Signs work because they don't have extra code preventing them from working in a water elevator. They don't make for super-fast water elevators, so there's no extra code to prevent their use. Oct 23, 2012 at 17:32

After lots of trial and error last night, I've figured out these:

  1. As mentioned by others, use signs instead of ladders.

  2. It is VERY important to make sure the tunnel leading to the water elevator is two-block in height, and make sure this 2-block high tunnel is reasonably long (at least 6-7 blocks) or else the mobs will be "set" back to the beginning of the tunnel (you see them arriving at the bottom of the lift, wait for a few ticks, then get instantly "teleported" back off).

  3. The bottom most water block should consist of 3 water blocks (perhaps to make the mob think it's in a pool), so that mobs will try to swim up.

Here's a picture of it

I couldn't explain many of these, but through experiments, mobs will not swim up if any of these three things are not met.

Also, you want to make sure the mob landing area is at least 17 blocks away from the spawner, for that mobs won't spawn if there already are enough mobs in this area. So the picture in Rory Alsop's answer won't make a good experience farm, although it serves well as a proof of concept.

(I apologize for answering my own question instead of accepting others. Thank you all for your inspiring answers. I've upvoted most of them.)

  • Also adding to the above design you can have the river feed vertically into the elevator. Here's and example of what I mean... Link
    – user42572
    Feb 17, 2013 at 18:35

I highly recommend Etho's videos for this. You can find his updated Mobavator here:

What you will want to pay attention to however is that mob spawners work differently than normal spawning.. You need to be close to them for them to be active so be sure you are not moving the mobs to a location where they will not spawn.

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