tranquil

characterized by absence of emotional agitation

• “calm acceptance of the inevitable”
• “remained serene in the midst of turbulence”
• “a serene expression on her face”
• “she became more tranquil”
• “tranquil life in the country”

(of a body of water) free from disturbance by heavy waves

• “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”