Why is Caribbean bottom water warmer than bottom water in much of the Atlantic Ocean?

The Caribbean Sea's bottom water is warmer than that of the Atlantic Ocean because the shallow sill depths of the Antillean arc act as a barrier, preventing the entry of cold Antarctic bottom water.1

While the Atlantic Ocean features significantly colder bottom temperatures of less than 36 °F (2 °C), the Caribbean Sea maintains a bottom temperature of approximately 39 °F (4 °C). Because the deep, frigid currents from the Antarctic are blocked by the submarine ridges and passages connecting the Caribbean to the open ocean, the basin is instead filled by warmer water masses entering through shallower channels, such as the Windward Passage and the Anegada Passage.12