Thalassophobia

Thalassophobia adds hostile sea creatures to ocean biomes. Most of them appear in regular oceans, while some appear only in deep oceans during the night, on the ocean floor. Spawn frequency varies: common mobs turn up often, while larger ones spawn less often and depend on luck with spawn rates. Most mobs use special spawning conditions, so they show up only under certain circumstances.

Two items handle detection. The Echoshell picks up nearby water mobs, and the Leviathan Sensor reaches a longer range but detects only leviathan mobs, a group that includes several large predators and the Sea Phantom. Both items work only underwater. The Sonar Beacon sends a sonar pulse that damages nearby water mobs, but it works only when the block sits above water and is activated through redstone signals. Sculk sensors are named as the preferred target block for it.

The mod requires Geckolib, and it runs on client and server, so the server and every player need it. Files are published for Forge only, for game versions 1.19.2 – 1.20.1. The author recommends the newest version, since it adds a shield, better structure generation and custom villagers that 1.19.2 lacks. Thalassophobia is released under All rights reserved, so it is not open source.