Carbon sequestration for mangroves and seagrass communities is greater than that of tropical forests, representing dramatic carbon storage opportunities for climate change mitigation. Global hotspots for blue carbon sequestration have been examined for the Gulf of Mexico (GOM), the Lower Caribbean (LC) and the Indo-Pacific (IP) region of Southeast Asia have been examined. Here we estimate carbon sequestration for the whole Caribbean coastal basin by including our own and published analyses of carbon sequestration and areal extent of seagrass and mangroves. We find far fewer measurements of blue carbon in the IP than for the GOM. The Caribbean has 26% of global mangroves. The 12-month productivity cycle of both seagrass and mangroves with their high growth rates is key to understanding their high annual carbon sequestration. Often seagrass and mangroves accumulate carbon of riverine origin. Nations bordering the Caribbean basin frequently have higher extents of seagrass than mangroves. For example, the northern part of the Caribbean, the GOM, has about 1 million ha of seagrass, and about 650,000 ha of mangroves. On the other hand, mangrove carbon sequestration values in the LC far outnumbers that for seagrass. However, measurements of areal extent by satellite in the clear waters of the Eastern Caribbean have shown high areal extent of seagrass, especially in the Bahamas.  The total mangrove extent in the Caribbean is estimated at 2,728,333 ha (650,000 ha in the GOM; 2,077,902 ha in the LC. The total seagrass extent in the Caribbean is 3,000,000 ha (1,000,000 ha in GOM; 2,000,000 in LC). Carbon sequestration in mangroves ranges from 282 Mg C ha-1 to 633 Mg C ha-1, leading to a total estimate of 1,276 Tg C in the combined Caribbean basins (476.13 Tg C in the GOM;  800 Tg C in the LC). Carbon sequestration in seagrass ranges from 50 Mg ha-1 to 254 Mg C ha-1, leading to a total estimate of 552 Tg C in the combined basins (184 Tg C in the GOM; 368 Tg C in the LC) . The total carbon sequestered by mangroves and seagrass communities in the Caribbean as a whole is estimated to be 1,828 Tg C. Clearly, the Caribbean basins are a carbon sequestration hotspot. Our total carbon sequestration estimate combined for mangroves and seagrass is lower than that of the IP region, which apparently is the highest in the world.  We hypothesize that the shallow seas, many kilometers of island coastline, and the “flow through effect”, (discovered by Klaus Wyrtke) of the IP region create ideal conditions for mangroves and seagrasses to sequester blue carbon. Such condition are not met to the same extent in the greater Caribbean.