stasis tank
A liquid-filled container (usually a tube or a tank) with transparent walls. Possible uses include keeping living organisms in stasis, accelerating growth or development after undergoing a cloning process, or even post-injury healing and recovery.
An archetypal stasis tank design can be seen in Danbooru post #607235. Science fiction commonly depicts people floating in these tanks, such as shown in Danbooru post #80217.
(Note that this tag can apply to a wide variety of containers/vats/tanks, as long as have a description and function similar to what is outlined above.)