a lake of tranquil blue water reflecting a tranquil blue sky.
a ribbon of sand between the angry sea and the placid bay.
a serene expression on her face.
a smooth channel crossing.
he remained serene in the midst of turbulence.
remained calm throughout the uproar.
scarcely a ripple on the still water.
she became more tranquil.
spoke in a calm voice.
the quiet waters of a lagoon.
tranquil life in the country.
unruffled water.