I read this with great interest. It seems to have been prompted by an experiment conducted with wine in France (where the ocean seems to have acted as a rolling fridge on the wine) and one conducted with Cognac where the spirit was shipped around the world - on top of the ocean - to hasten and improve maturation. Shipping spirits to improve quality has a rich history and bourbon and rye were shipped as well in the 1800's for reasons similar to those explained on the Kelt website. I used to drink Linie Acquavit (referred to in the Kelt website) and it is very good, and I will buy some Kelt to try that too. In America, bourbon was shipped out easterly to Bremen, Germany and to points in England, and also east and south to South America, partly at least to delay imposition of taxes. Even bourbon shipped downriver on flatboats over the American river system improved in quality and this may have prompted in fact methodical barrel aging of bourbon and rye in warehouses.
With respect to the Grand Cayman rum, I am wondering if the rolling effect of the seas could be achieved by tethering a barge holding the barrels on the coast. The humidity would be different of course. This way you would get the effect of the angel's share, but maybe the Cayman's producer doesn't want that. Bas' question is an interesting one. If the barrels are in a watertight container underwater, perhaps the spirit still leaves the barrel in a way similar to that on land and stays (the vapors) in the container until opened. Or maybe relatively little spirit gets out (the humidity factor, like in Scotland), which would be good from a production standpoint - less of a wasting asset. They must protect the barrels in some way from seawater.
I know we had discussions here some years ago (I participated) in the history of the sea export of bourbon and rye from America to help the aging process or benefit from its results. Searches under "Bremen", "Brazil" and "ocean" should bring these up.
I will pick up this rum when I next see it in the States. I like the concept of undersea aging, which offers probably some kind of interesting effect on the spirit and is a good business (marketing) concept too. I wish them well. Thanks again for the heads-up.
Just on small barrel re-aging or finishing of bourbon, a number of experiments were conducted by members of http://www.straightbourbon.com
and I tasted some of the results. I didn't use any in blending, not that I didn't want to, but never had enough. The experiments were interesting. Truth to tell, in most cases I found the effect added an extra flavor, a pine-like note that did not assist the whiskey. I am not sure why this occurred. It might have come from the particular small barrels used, or perhaps the right cycling did not take place in the areas where this was done (some on the West Coast). Or maybe the aging needed to be more prolonged than it was for the ones I tried (generally a few months to a year). In some cases, a blend of bourbons was used, in others, a combination of one or more bourbon and GNS (to get the entering proof up). These were excellent experiments conducted by some great people. I believe I had some influence (amongst others) in suggesting some of the early experiments.