This mod add a new block to the game that allows the player to create barriers that only block fluids such as water and lava, and let the player go through them.
Very useful for water elevators constructions!
First get the block using the comand <give @a brbmods:fluid_barrier_block [quantity]>
Equip it and use it like any another block.
If you have the block equipped in any hand you will be able to see the block. If you drop it, the block will hide.