Hot springs structure.

A structure which is can generate or only made by hand.

It requires potent sulfur block, which under it has soul soil, is surrounded by water and on top of it is soul sand(Or new special blocks). These work as a filter, filtering out the noxious chemicals out of the sulfur.

The soul sand has on top water(1 or 2 blocks deep), the water turns less translucent and vapor comes off it. The smallest size is 1 block and biggest is 16 blocks. It doesn't require to be a square, just needs 16 blocks of water. The bigger the hot spring, the longer duration effects it gives, however it takes longer for them to apply.

The effects are regeneration and new effect called "rested". The rested status effect slows hunger and saturation loss by 40%. The max duration for both is 10-12 minutes.

The water also can't freeze.