During our workup’s four-week dive phase, I had a new and unique underwater combat experience: going up against dolphins.
In their arsenal of defensive strategies, the EOD (Explosive Ordnance Disposal) guys sometimes use sea lions and/or dolphins as a front line of harbor defense. They outfit these animals with a device strapped onto the head that contains a compressed gas needle, and train them to track down enemy divers. Once the dolphin has tracked you down, it butts you; the needle shoots out and pokes you, creating an embolism. Within moments, you’re dead.
Obviously, they didn’t use the actual device on us, but they had training devices that looked and behaved just like the real thing. When a dolphin succeeded in nailing you, a little foam float would pop up to the surface, indicating that you’d been “killed.” The dolphin would then swim to the surface and be rewarded with a sardine. You, on the other hand, would be rewarded with a low score — or with having to do it all over again. Those suckers really packed a wallop. I heard that when you got nailed, you’d be sore for days.
Chief Dan was my partner on this exercise. We could tell when those little bastards were approaching because we could hear their sonar clicking — but that didn’t make it any easier to escape them, because they swim fast, way too fast for us or any other human being to outrun them.
As a rescue swimmer, though, I’d worked with sonar, and I was pretty sure I understood how the dolphins’ sonar sense worked.
“If we stay shallow enough,” I told Chief Dan, “and stay close enough to that big rock breakwall, it will mess with their sonar. They won’t be able to get a good return signal.”
That was our strategy close to shore. Farther out, where there was no way to screw up their sonar, we decided to try using thermoclines to our advantage, going deep and taking care to keep a solid temperature break in between us and the dolphins.
We didn’t get hit once.