The term "capricious sea" refers to an unpredictable and moody body of water. However, there are other synonyms that can be used to describe such a sea. The sea could be termed as erratic, fickle, or changeable due to its sudden and unexpected shifts in its temperament. Another synonym for a capricious sea is mercurial, which implies a constantly changing nature like the Roman god Mercury. The sea could also be called turbulent, tumultuous or tempestuous, which depicts its erratic and sometimes destructive nature during storms and high winds. In conclusion, these synonyms provide alternate ways of describing the nature of the sea, highlighting its unpredictable character.