under Water stuff

So I have this idea for an under water exploration mod, here is a few of my ideas:

1. Scuba Gear(flippers,mask,breather,wet suit,oxygen tank)

2. Oxygen tank refill station, because no oxygen tank has infinite amounts

3. special caves in oceans that contain treasures and mobs

4. Mobs(shark,whale,kraken,etc.)

I fell this is a very good idea for a mod but im not sure If i can do it alone or even do it at all!

thanks for reading and hope you suggest ideas or ways to help