General synonyms:
* Calm
* Peaceful
* Serene
* Quiet
* Still
* Relaxed
* Unruffled
* Composed
* Placid
* Untroubled
More specific synonyms:
* Peaceful: Implies a sense of absence of conflict or violence.
* Serene: Suggests a sense of calmness and beauty.
* Quiet: Emphasizes the absence of noise or commotion.
* Still: Describes a lack of movement or activity.
* Relaxed: Indicates a state of ease and comfort.
* Unruffled: Conveys a lack of disturbance or agitation.
* Composed: Implies a state of being in control and collected.
* Placid: Suggests a gentle and peaceful demeanor.
* Untroubled: Highlights the absence of worry or anxiety.
The best synonym to use will depend on the specific context and nuance you want to convey.