These are essentially water markers. See something in the water you want to go back to? Drop one and done. Also, they make some brilliant spark shows when they first hit the water!

TO USE:
STEP 1: First off, get this thing mounted on a wingtip, away from anything that the bullets might hit from the side.
STEP 2: Fly up and over water, where you can reliably drop one.
STEP 3: This is the most important step. Fire and hold the guns for a while, and while they are shooting, press the activation group that you assigned the detacher to and the bomb will drop. And, while the gun fires as it falls, it should do so indefinitely.

Once it hits the water, take a look. It will at first disappear, then explode into a huge fan!