See that bar at the bottom of the screen when you're in the sea? That's the 'Gold Rush' bar. Every time you earn points, that bar fills up a little bit. When it fills up to the top, you trigger 'Gold Rush' mode. Now you have a short window of time where everything you can eat turns gold and gives you coins. Also during a Gold Rush, you have infinite Boost! And to top it all off, you're also invincible for as long as it lasts. How amazing is that? Well worth it.