Shark/boat screenshot is good. We need screenshots that imply gameplay, which is harder to capture than just something cool looking.
I have this picture of Lord Tony which is quite Action-Filled. Although I don't know if we need to boost his ego by putting it on the Greenlight Page
There's also this
really old picture, pre v8, of you and a few other coolguys having a sword fight on my bridge.
Also may I suggest the default Artillery Attack pic?
I don't have many other Action or Gameplay screenshots. Maybe afk at your Pirate DM for a while and take some pics?