Example : The waiters were unflurried and good natured.
With contented mind and unruffled spirit.

Synonyms : unflurried, unflustered, unperturbed

Example : A ribbon of sand between the angry sea and the placid bay.
The quiet waters of a lagoon.
A lake of tranquil blue water reflecting a tranquil blue sky.
A smooth channel crossing.
Scarcely a ripple on the still water.
Unruffled water.

Synonyms : placid, quiet, smooth, still, tranquil