How does co-location work with Army & Navy? If possible, which locations are there?

The only ones CONUS that I can think of are:
+ Joint Base Dix-McGuire-Lakehurst
+ the US Army Special Operations SCUBA School at Key West, FL
+ the Navy Diving School in Pensacola, FL trains Army Engineer Divers
+ Fort Eustis (Joint Base Langley-Eustis) is located near Norfolk and NAS Oceana

Army and Navy would be a hard mix. My ex is a 12Y and I am a Corpsman; we talked about this briefly before she and I went separate ways. Sadly there is no guarantee of co-location, only that "reasonable efforts will be made." On a good note there are many Joint bases throughout the military and often times there will be multiple branches within 100 miles of each other.

On a no bs assessment, they had better be ready because i can almost guarantee they will do a tour apart sometime in the future.