Gustlantic

This mod adds new blocks, items and mobs on the theme “Underwater”

A new item: the shark tooth

You get the shark tooth by killing a shark. You can make a block or a sword that does more damage to aquatic mobs out of shark teeth. The sword has 3 tiers. Tier 1 is a normal sword. 
Tier 2 is the extended variant of Tier 1, hitting faster and doing more damage. Tier 3 is the ultimate fusion of two tier 2 swords. Tier 3 does more damage but hits slower.

The throwable harpoon is the second weapon in this mod and is good for chasing fish.

Another useful item is the Diving Helmet.
The Diving Helmet, craftable with 3 coppers, a glass pane and a turtle helmet, ensures that you can breathe underwater.

This mod also adds a new coral. 
The coral is green and is called "grow coral". You can find them like other corals in coral reefs.

You can craft new blocks from this coral.

There are also four new mobs.
The shark that drops shark teeth, the mermaid that can't do anything yet but for which great features are still planned, the giant squid that spawns in deep oceans and the whale that also spawns in deep, 
colder oceans.

I wish you a lot of fun with the mod. If you have any questions or find a bug, then join my Discord:

https://discord.gg/NuB7DukdAA