Right in the middle of the circular gardened area just east of the Hunter Quarry.
You can jump to the wall from the house next to the safehouse.
A horseshoe and oyster in the pool here, bonus!
Next to the fence in the northwest corner of the airport. Hard to spot if you're facing the fence.
Keep an eye out for this one while you're on the 'Up, Up and Away' mission. It's out the back of the first warehouse you clear of soldiers.
This one can be tricky to spot as it's inside the corner of the building on the next level up from ground. Look for the 'Parking' sign on the northwest corner of the building.