Several questions here related to mobs and water:

  1. When mobs enter water, do they swim at the top, or will they dive down?
  2. Can mobs spawn in the water?
  3. I assume mobs can exit water one block deep, but can they climb out from a deeper sheer edge? (Players can, right?)
  4. Is there an easy way to make a shoreline mob-proof (without actually using a wall or fence?)

Thanks for the help.

  • 17
    "Fun" fact: Skeletons / Zombies in the water don't burn up in sunlight. – Raven Dreamer Apr 15 '11 at 16:49
  • 14
    that's not fun at all, actually. – JoséNunoFerreira Apr 16 '11 at 2:36
  • I'd like to suggest an addendum to this question: Will mobs spawn 'in water' if it is one block shallow, or does water prevent all mob spawning besides squid, period? – Zibbobz Jul 16 '14 at 19:07
  • 1
    @Zibbobz "one block shallow water" counts as just water, and will prevent non-water-based mobs from spawning. This can also be done with a single layer of transparent blocks, half-blocks (like slabs or stairs), or lava. – Keaanu Aug 14 '18 at 20:13
  1. Most mobs swim to the surface, even if you're submerged beneath them. The exceptions are:

  2. Most mobs will not spawn in or on water. Again, this comes with the exceptions:

    • Squids can spawn in any body of water, as far as 18 blocks below sea level
    • Dolphins spawn in non-frozen ocean biomes
    • Fish spawn in various places underwater
    • Guardians/Elder Guardians spawn in and near Ocean Monuments
    • Drowned mobs spawn at the bottom of oceans, rivers or swamps
  3. Since most mobs swim to the surface of standing water, they can get to the top of a sheer edge and exit from there. No mobs can swim up waterfalls though, so you can keep them all down using running water. Non-Drowned undead mobs will stay at the bottom of water and will be unable to escape.

  4. A long Soul Sand gate can be built along the shoreline, which will prevent mobs from crossing it. These gates can be traversed by players using minecarts on tracks placed over the Soul Sand. From the wiki:

When placed on the ground in front of a two-block high doorway, soul sand prevents players from going through it from that direction, making it useful for building one-way passages or invisible barriers. This affects mobs too as they have to jump to get out of the slowing effects of the block, thus are unable to get through the door.

Because minecart tracks can be laid on Soul Sand like most other block materials, this quirk can be exploited to create minecart-only gates (by placing soul sand on both sides of the doorway). This is one of the few ways to allow minecart tracks to go directly inside a secure area without risking wandering mobs getting in.

Here's a snapshot of a small one I built beside my house, with a crossing point for players.

A Soul Sand gate along a small shoreline

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  • 1
    I assume the gate you detail wouldn't work against spiders, pigs, or chickens? – Nick T Apr 15 '11 at 20:11
  • @NickT make it 1 block wide, and spiders will keep out. – Mindwin Nov 18 '15 at 10:58
  • 1
    As of 1.13, zombies no longer swim, and drowned can swim and will attack underwater players. – pppery Aug 14 '18 at 16:20
  • @ppperry Cool. Updated to post-1.13 Bedrock Edition mechanics. – Keaanu Aug 14 '18 at 19:55
  • You've forgotten that Husks turn into zombies when underwater, also your drowned link goes to phantoms instead of drowned – pppery Aug 14 '18 at 20:21

To answer the first question:

When mobs enter water they swim to the surface. My son has built a mob "generator" which relies on this principle to draw the mobs to the surface where they die and deposit their goodies for him to collect.

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  • 6
    Answering through my experience how dare you! – Ronan Apr 15 '11 at 16:03
  • 6
    @Ronan - Fastest Gun In The West! Wins every time. Feel free to add your own answer that addresses the other points. – ChrisF Apr 15 '11 at 16:04
  • 12
    First father son combo I have seen on here. +1 for being awesome! – theorise Apr 15 '11 at 16:07
  • 3
    @Ronan - nope - it's "waiting for a build" – ChrisF Apr 15 '11 at 16:08
  • 2
    @ChrisF - You could instead be sword-fighting ya know. – Sadly Not Apr 15 '11 at 16:43

Eventually, Mobs will die if in water too long. Squids will not die, but they are not mobs and will not harm you. (Note: Squids can't swim upwards. I hope this is useful in case you ever find a squid farm!)

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  • 4
    Squid are mobs – just passive mobs. – SevenSidedDie Sep 18 '11 at 0:37

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