New Game: Captain Quickhook's Revenge

I’ve been working on this game for a few weeks. It started out as an experiment to figure out double jumping, but has become deeper and more intricate. I am about halfway through the game; that’s three levels since I am on a free account. I designed the levels to have places to explore and short-cuts, though they are still short (but longer than those in my first game).
Each island, as the levels are called, has a different music style, aesthetic, and boss character. The levels become more challenging, but you have a health bar of three. Each island also has at least two checkpoints. Since you may have played other games in flowlab with long (and sometimes repetitive) levels, instant death hazards, but no checkpoints, I wanted this game to be different (kudos to Latif’s Cube’s Adventure for the behaviors of a checkpoint). My game also features water physics that are based on proximity to water (also @Latif inspired).
Captain Quickhook and the first two bosses have decent animations, but I still need to work on the animations for the enemies. I also plan on having a coin counter at the end of the game that gives the player a rank depending on how many doubloons they survived with. This behavior will probably be tied to the ship since it is kept between levels.

Link to the game below:
http://www.flowlab.io/game/play/932888