I have also based and started to paint a 1/700th scale Hobbyboss Type 033 Romeo class submarine, which I had already cut down to the waterline. This won’t play an active role in games, as there are no rules for submersibles, but will be an ideal scenario hook, perhaps running aground or breaking down while in enemy waters, which has happened before to Soviet Romeos in the Baltic. It’s a really nice model too!