If you're referring to Shantae and the Pirate's Curse, the map is not totally Metroidvaniash, but everything else about the game is. You start in a town, and from there you can "sail" (i.e. teleport) to other islands. When you beat the boss of one island, you unlock the next island. Each island has an explorable map, and you find things on one island that help you progress on another. Even after you beat an island, you sometimes have to go back later with a new ability to explore more. It's a great game with a really nice soundtrack and beautiful pixel art and animation. I still consider it a Metroidvania. I've played the first few hours of the first Shantae, and have beaten Risky's Revenge and Pirate's Curse. I consider Pirates Curse the best of the three.