Addon: Aqueous Depths (New Ocean Biomes + Ocean Overhaul)
Author: rune_the_shadowmage
Aqueous Depths is a broad ocean overhaul with new environments, structures and an ecosystem in which creatures behave as prey, neutral animals or predators.

The Drenched Void descends through dark foggy water, Thermal Seas mix magma with floating islands, and Glowing Oceans use luminous stone and wildlife. Dread Reefs, island-filled seas and towering iceberg regions complete the biome set.

Passive life includes clams, jellyfish, shrimp, snails and reef creatures. Clams can be opened with shears for biome-dependent pearls. Merfolk trade when unprovoked; adopted young can grow into armed companions. Neutral creatures include urchins, Bubbalings, Magma Puffers and several ruin guardians.

Predators range from giant squid and drowned sharks to latching magma creatures, ambush hunters, giant isopods and lethal Titan Clams. Chum can deter many predators, but not every one. Minibosses such as juvenile Void Wyrms and Drenched Squids occupy the most dangerous areas.

The add-on needs no experimental toggles. Vibrant Visuals is currently incompatible.
How to install the add-on
Download the .mcaddon or .mcpack file, open it with Minecraft and wait for the import to finish. Then enable the resource and behavior packs in the world settings. If the add-on requires experiments, turn them on before launching the world.