Jacuzzi
A jacuzzi is a player-made structure. It will regenerate a blockhead's lost health and increase their environment bar.
Appearance
A jacuzzi is nothing more than a pool of standing water that is hot enough to steam. Steam appears as light gray particles rising from the water.
Building
A jacuzzi is made by heating up water. This is done by placing enough crafting surfaces that have flame effects (campfires, kilns, furnaces, metalwork benches, and steam generators) near standing water.
Don't heat it up too much, or it will become a boiler!
Notes
The jacuzzi will not send the blockhead's health and/or environment into overdrive, along the lines of the myth with coffee cherries and coffee.