To get to Gun Beach, follow San Vitores Road (the main road in Tumon) as far north as you can, past the Westin and Nikko Hotels, down the dirt road to the beach.
The best way to enter this dive from the beach is simply to follow the cables which cut through the reef directly in front of the parking area. The cables can be followed to the cut in the reef where it drops to about 15 feet, sloping down to 130+ feet.
Head either right or left of the cables, as both ways offer large coral heads and abundant marine life.
There is a small cave to the left of the cables at about 15 feet. To the right there are also several large holes which hold a variety of fish.
This is a good night dive, with cracks and crevices hiding many nocturnal creatures.