This work will attempt to better understand the renewal of water in the Central Caribbean Basins by direct measurements of the flow from the Atlantic through the Anegada-Jungfern passage, over the controlling sill into the Caribbean. Water properties, along with radioactive tracer distributions, will also be measured, both inside the Caribbean, and in the open Atlantic, in order to determine residence times and renewal rates. Theoretical analysis will focus on convective boundary flow dynamics, and their relation to water mass evolution in a confined basin.