I guess I'm wrong since it hasn't been mentioned, but I thought ALL marine exhausts had to be "wet" exhausts to pass CG approval.
It's an open question, however, where the "wet" part enters the equation. Most marine exhausts are wet for reasons of noise, not safety, although obviously an f/g boat will burn easier than a steel one.
In the example above provided by Kaluvic, the mixing elbow is below the waterline, but also ahead of the "turn" of the exhaust, which to my mind has many advantages over the more typical "mix in water just past the manifold and down a bit", because the waterlift and the anti-siphon valve in the typical "loop" can be points of clog or failure or backsiphoning due to sea conditions or overcranking.
I've
had such failures, and now before we go tootling around the world, I want to solve them in a permanent way.