It's probably not going to be very easy to identify the top two pictures, but the bottom picture appears to be the light cargo ship USS Mark (AKL 12). Note that Wikipedia uses its WWII registration number - see the hull's entry on the Naval Vessel Register.
Image from http://www.mrfa.org/akl12.html
The photo paper stamp would put the ship in theater during Vietnam, where it both ran supplies and assisted in supporting the "Brown Water navy" operating in the Mekong Delta. That would date the photo sometime between 1966 and 1969 (probably later based on the stamps on the back of the print).
You can find some additional information about the ship's service history at the Mobile Riverine Force Association website.