Surface Tension

Most additions are built for ocean-facing homes under the water. Decorative pieces sit on the seabed, and sand and gravel variants release bubble entities below the surface. Bubbles also rise in underwater caves, replenishing air for players who swim there. Plankton bushes emit plankton particles around themselves, and a barnacle cluster placed one block below a 3x3 grid grows after a while. Tension rods and geyser blocks are part of the set, with crafted copper block variants.

Several blocks change how water and movement behave. A tension rod prevents water from flowing downward across a 3x3 grid, and a block placed in a shaft lets entities travel up through it while moving down is unaffected by gravity. Dried cod and salmon are decorative blocks meant to hang above campfires, and eating the dried fish gives 10 seconds of Water Breathing. Shipwreck chests can hold some of the blocks, and placed barnacle clusters come in three sizes.

Surface Tension is a Fabric mod for 1.21.1 that runs on client and server, so the server and every player need it. The mod is released under the MIT License and is not open source. Its files are published only for Fabric, and the issue tracker is the public link for reports.