ZombieMod ReForged

2026-08-25. The Undertow swims. In 3.1.0 it did not.

Fixed

• The Undertow bobbed at the surface instead of swimming. It shipped with a float goal, and FloatGoal calls JumpControl.jump() on every tick it spends in water — which pins a mob to the surface and bounces it there. Harmless on the genus the goal list was copied from (the Bogman is amphibious and walks the bottom, where floating is correct) and completely wrong on a swimmer.

  Its idle wandering was broken too, for a separate reason: random_stroll picks destinations on land, so a swim navigator was being handed places it could not path to.

Added

• A random_swim goal type, which is what navigation: swim had been missing. The navigator plans a route through water but nothing was choosing anywhere to go — the same shape as climb, where the spider navigator plans the climb and ClimbGoal performs it, and neither works alone. swim had the planning half only, and no genus had exercised it until the Undertow.

  Datapack authors: give a swimmer random_swim rather than random_stroll, and do not give it float.

Requirements: Minecraft 1.21.11, NeoForge 21.11.42+, Java 21. Install on the server. Your players do not need the mod — a stock client can join and meet every genus. Installing it client-side too is optional and adds the ZombieDex screen.