Crawling and flying? Avoiding feature creeping

Going mad
Why can't I make this thing fly!? 
I could make each level a self contained island.
You get from one island to another by air, maybe unlocking another gameplay altogether, a brand new part of the vehicle that forces you to learn once more new controls, thus breaking monotony!
You can acquire the next island coordinates, getting what you need before to set course and take off, seems like a very fun and motivating excuse to exploring as much of each island as possible, F*YEAH!!
So, how do you fly though?

At this point, I have little time at disposal and I'm almost done with the core part of the game, which I believed to be most of the game itself before going down this rabbit hole.
I have a payed job and little time to make progress, I am definitely caught in feature creeping, but oh boy they are such cool features too!

Going up, screw it, it doesn't get any cooler than that, the Nauticrawl can fly!
Fast forward to a couple of weeks before I wrote this post, my employer decides he's run out of money and it's time to shut down the game I was making for them.
Too bad, but at least now I have the time I needed to at least start this new section of the game.
Enter the Zeppelin module of the Nauticrawl! Activated once you've collected the Crystal, found the next island coordinates and you feel like you are ready to take off.