Sea cradle is a phrase that refers to the rocking or undulating motion of the sea. It can also describe a small boat or vessel that is bobbing up and down on the waves. If you are looking for synonyms for the phrase, there are many options to choose from. Words like ocean bed, saltwater cradle, briny basin, aquatic hammock, and tidepool perch are all suitable alternatives. Other options include seafaring cot, marine manger, waterborne bower, nautical nest, and maritime swing. Whatever term you choose, it should convey a sense of the soothing motion of the sea and the feeling of being gently held in its embrace.