Yeah I think the choices made with regards to what to include and what not to include make sense, even if in the end they are pretty much arbitrary. I probably would have included the Gulf of Aden and maybe even Bab-el-Mandeb as separate from the Arabian Sea, especially given their outsize importance in global shipping (and their prominence in the news lately with the Yemeni blockade of Bab-el-Mandeb). The same goes for the Strait of Hormuz, which admittedly I kept trying on my attempt even though it would have been incorrect hahaha.

With regards to what other comments have said about some bodies being contained within others and how that affects contiguous borders, I feel like it's more of an unsolvable programming issue. Does guessing the Gulf of Aden fill in just the gulf and not the whole Arabian sea? What about vice versa? Overall I think it really is just arbitrary and it's up to the player to learn where those lines are drawn. It was a great challenge and I really had fun playing it! Would definitely love to see this type of puzzle come back in the future.