I guess I should feel somewhat bad for doing this, but it was the most hilarious use of my Locust so far. I activated submarine mode on River City, and not a bit of my 'mech was showing. If you want to make your team laugh, go ahead and give this a try. And it still remains about as tense as any match in a Locust, only this time you're worried that the Atlas five metres from you will see you and absolutely decimate your poor little thing.
They didn't even fire on me. I know mechs can be seen underwater, but nobody saw me. Which is actually weird, because those antenna were above the surface. It was a scary experience, but quite funny as well.