Swim in refers to the action of immersing oneself in water and moving around inside it. There are several synonyms for this term, including splash around, wade in, dip, dive, plunge, and paddle. These verbs can be used depending on the specific context, such as the depth of water, the purpose of swimming, or the style of swimming. For example, someone can wade in shallow water, whereas, they can dive into deep water. Similarly, if someone wants to play and enjoy in the water, they might splash around or paddle around, rather than diving in. In short, these synonyms for "swim in" provide different ways of describing the experience of being in the water.