North Los Santos
Bridge Location 12: These next few bridges can be found by traveling up the aqueduct, continuing from Bridge 11.
Bridge Location 13
Bridge Location 14
Bridge Location 15
Bridge Location 16: Easily one of the more difficult bridges to get under in the game. Your best bet is to grab yourself a Buzzard helicopter to get through.
Bridge Location 17: Found right after #16, this bridge is just as difficult. Make sure to get yourself the Buzzard chopper to make things easier.
Bridge Location 18: Head south on the Del Perro highway from the previous bridges and you will come across this bridge and the next two right after another.
Bridge Location 19
Note: Bridges 20-27 are located in South Los Santos.
Bridge Location 28: Take a cruise up the 5 along the east coast and you will come across this train bridge.
Bridge Location 29: Located just north of the previous bridge, this one is a little easier to get under when approaching it from the east side.
Bridge Location 30: One of the more sneaky "bridges" in the game, this arch can be found just to the south of the Power Station.
Bridge Location 31: Located to the southwest of the Power Station, you will come across these next two bridges located right beside each other.
Bridge Location 32
Bridge Location 33: This bridge, located on the opposite coast, can be found near Chumash, along the Great Ocean Highway. There are two identical bridges, but you'll only get credit for one of them.