The phrase "sinks into" refers to something gradually merging or becoming lost in something else. There are various synonyms that can be used to describe this action, including submerges, settles, plunges, immerses, disappears, embeds, and assimilates. When an object or substance is gradually disappearing or getting absorbed into something, the phrase "sinks into" can be replaced with any of these synonyms. For instance, "the sugar dissolved in the tea," "the sun plunged below the horizon," "the sunken ship settled on the ocean floor," "the fish immersed themselves in the water," "the words embedded themselves in my memory," and "the cultures assimilated over time." These synonyms can bring more variety and color into our writing and help to avoid repetition.