Skifree! It's crazy that you had the yeti from Skifree as the end game beasty. I had this funny nostalgia of Skifree while I was playing, slaloming between obstacles and what not. The fact that the yeti made an appearance caught me totally off-guard and blew me away. Nice.
Seriously though, this is a nice little game. Sure, it's been done a hundred times, but it still felt fresh enough to me. Maybe it was the art style, and admittedly I'm a sucker for visible, unique upgrades. What would REALLY be neat and innovative is if after descending back down and diving into the water, you had an 'inverse' mode where you went towards the bottom of the screen as a submersible. The momentum from your fall would be the launch. Eh? Why the hell not.
Tl;dr: Wewt, yeti! Make a submarine mode!