Forbes brings us an article by blogger H I Sutton (Covert Shores), probably the best unclassified source on maritime smuggling technology in the English language, reporting discovery of an exceptionally large self propelled semi-submersible seized by Colombian forces before it could sail. The mystery is why so large and what was it expected to do? My guess–going to the Western Pacific for transshipment somewhere in Oceania.
Chuck Hill's CG Blog 
Interesting read Chuck, thanks for the link. Sutton noted that the trend appeared to be going toward smaller, more numerous narcosubs, likely in an effort to decrease the financial hit on cartels from interdictions…this certainly goes against that mindset.
I think maybe it means greater range and perhaps less chance of being intercepted by avoiding the usual transit routes.