Axel & Pixel

This one is fairly simple and if you beat this level and got all the bones in the campaign, you'll be ready for it. The bones are placed in much trickier spots than the point stars are, so you'll be traveling in a much more straight line while doing small adjustments along the way. Don't bother going for small stars unless they're very close and make sure you avoid obstacles. Remember that you don't have to dodge whirlpools very widely; you can just narrowly cruise past them.

The trick to playing this minigame easier, I find, is to put the little propeller icon in front of the ship and just make minor adjustments to the up and down momentum. Doesn't really make any sense and isn't how they want you to play, but keeping the propeller behind the boat just causes unwanted speed boosts and lack of control.

This one took me two attempts to complete, so it isn't very hard.