I like both the original border and the new coloured one. I can't decide which is best. I think I'd need to see more features on the map before I commit. If there are a lot of brightly coloured elements, then a neutral border might be better. Not sure yet.

Skull island is my new favourite thing! I also love the little mermaid.

Have to second the comment that the mountain is very dominant at the moment, but I'm waiting to see what appears in the surrounding area. I will say it's well drawn and looks good, so I'm looking forward to seeing what you do next.