Nothing special about the nail gun. The tittle should have been using a pneumatic nail gun under water.
Back in the middle 1980s when I had a dock building company, I used my Paslode gun under water a lot of the time nailing 3 1/2" coated ring shank nails. New construction wasn't bad but when having to do repairs on older construction the discharge made the water so cloudy with Alge you had to wait until it cleared or just nail by feel alone.