SF 340B
Flight Crew Commercial; Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor
Flight Crew Last 90 Days 200; Flight Crew Total 1950; Flight Crew Type 1350
Conflict Airborne Conflict
Flight Crew Took Evasive Action
Airport; Procedure
Handed off from Miami Center to Nassau Approach overhead RAJAY intersection enroute to MYNN airport. NAS Approach cleared our flight to descend from 11;000 feet to 2000 feet and proceed direct to MUNIE intersection. My FO read back the clearance and clarified the fix; and as I initiated the descent I looked up to see a Cessna Caravan approaching; opposite direction. I stopped the descent and returned to 11;000' as the Caravan passed 500' directly below.  We advised Nassau approach that we had deviated to avoid a collision and were advised that they '...don't know anything about that aircraft. We aren't talking to them.'In this situation; after receiving a clearance to descend with no traffic advisory issued; it was left to eyesight and reaction time to avoid a collision; especially at a closure rate near 400 knots.  This being the third RA that I've experienced in Nassau's airspace--almost always just inside of RAJAY--I feel that it is an issue that needs to be addressed.
An SF340 flight descending into MYNN; cleared to descend to 8;000 feet; narrowly avoided an NMAC with an opposite direction Cessna Caravan.  Approach advised they were not talking to them.