The mod will add a set of diving equipment, which will increase the speed of movement and breaking blocks, but on land you will become slower and slow.
Simple Diving Gear Mod for Minecraft 1.15.1/1.14.4
You can also make one upgrade for bright coverage of the territory you are exploring. Now you can explore the underwater bottom in Minecraft and find something interesting there.
1.15.1 – SimpleDivingGear_4.0.0mc1.15.1
1.14.4 – SimpleDivingGear_3.0.4mc1.14.4